Author: paul
Date: 2010-10-15 18:21:16 +0200 (Fri, 15 Oct 2010)
New Revision: 23159
Log:
r64250@frost: paul | 2010-10-15 11:17:51 -0500
Precision-math and data-type revisions
Modified:
trunk/refman-4.1/functions-core.xml
trunk/refman-5.0/data-types.xml
trunk/refman-5.0/functions-core.xml
trunk/refman-5.0/precision-math.xml
trunk/refman-5.1/data-types.xml
trunk/refman-5.1/functions-core.xml
trunk/refman-5.1/precision-math.xml
trunk/refman-5.5/data-types.xml
trunk/refman-5.5/functions-core.xml
trunk/refman-5.5/precision-math.xml
trunk/refman-5.6/data-types.xml
trunk/refman-5.6/functions-core.xml
trunk/refman-5.6/precision-math.xml
trunk/refman-6.0/data-types.xml
trunk/refman-6.0/functions-core.xml
trunk/refman-6.0/precision-math.xml
Property changes on: trunk
___________________________________________________________________
Name: svk:merge
- 07c7e7b4-24e3-4b51-89d0-6dc09fec6bec:/mysqldoc-local/mysqldoc/trunk:35498
07c7e7b4-24e3-4b51-89d0-6dc09fec6bec:/mysqldoc-local/trunk:43228
4767c598-dc10-0410-bea0-d01b485662eb:/mysqldoc-local/mysqldoc/trunk:43968
4767c598-dc10-0410-bea0-d01b485662eb:/mysqldoc-local/trunk:44480
7d8d2c4e-af1d-0410-ab9f-b038ce55645b:/mysqldoc-local/mysqldoc:64242
b5ec3a16-e900-0410-9ad2-d183a3acac99:/mysqldoc-local/mysqldoc/trunk:14218
bf112a9c-6c03-0410-a055-ad865cd57414:/mysqldoc-local/mysqldoc/trunk:39036
bf112a9c-6c03-0410-a055-ad865cd57414:/mysqldoc-local/trunk:39546
+ 07c7e7b4-24e3-4b51-89d0-6dc09fec6bec:/mysqldoc-local/mysqldoc/trunk:35498
07c7e7b4-24e3-4b51-89d0-6dc09fec6bec:/mysqldoc-local/trunk:43228
4767c598-dc10-0410-bea0-d01b485662eb:/mysqldoc-local/mysqldoc/trunk:43968
4767c598-dc10-0410-bea0-d01b485662eb:/mysqldoc-local/trunk:44480
7d8d2c4e-af1d-0410-ab9f-b038ce55645b:/mysqldoc-local/mysqldoc:64250
b5ec3a16-e900-0410-9ad2-d183a3acac99:/mysqldoc-local/mysqldoc/trunk:14218
bf112a9c-6c03-0410-a055-ad865cd57414:/mysqldoc-local/mysqldoc/trunk:39036
bf112a9c-6c03-0410-a055-ad865cd57414:/mysqldoc-local/trunk:39546
Modified: trunk/refman-4.1/functions-core.xml
===================================================================
--- trunk/refman-4.1/functions-core.xml 2010-10-15 15:15:18 UTC (rev 23158)
+++ trunk/refman-4.1/functions-core.xml 2010-10-15 16:21:16 UTC (rev 23159)
Changed blocks: 2, Lines Added: 5, Lines Deleted: 6; 1230 bytes
@@ -5641,12 +5641,11 @@
<listitem>
<para>
- If one of the operands is an unsigned integer, and the other
- operand is also an integer, the result is an unsigned
- integer. For subtraction, if the
+ If both operands are integers and any of them are unsigned,
+ the result is an unsigned integer. For subtraction, if the
<literal role="sqlmode">NO_UNSIGNED_SUBTRACTION</literal>
- SQL mode is enabled, the subtraction result is signed even
- if any operand is unsigned.
+ SQL mode is enabled, the result is signed even if any
+ operand is unsigned.
</para>
</listitem>
@@ -5683,7 +5682,7 @@
<para>
For information about handling of overflow in numeric expression
- evaluation, see <xref linkend="numeric-types"/>.
+ evaluation, see <xref linkend="out-of-range-and-overflow"/>.
</para>
<para>
Modified: trunk/refman-5.0/data-types.xml
===================================================================
--- trunk/refman-5.0/data-types.xml 2010-10-15 15:15:18 UTC (rev 23158)
+++ trunk/refman-5.0/data-types.xml 2010-10-15 16:21:16 UTC (rev 23159)
Changed blocks: 1, Lines Added: 4, Lines Deleted: 4; 1168 bytes
@@ -2370,10 +2370,10 @@
<literal role="type">REAL</literal>, and
<literal role="type">DOUBLE PRECISION</literal>). The keyword
<literal role="type">INT</literal> is a synonym for
- <literal role="type">INTEGER</literal>, and the keyword
- <literal role="type">DEC</literal> is a synonym for
- <literal role="type">DECIMAL</literal>. MySQL treats
- <literal role="type">DOUBLE</literal> as a synonym for
+ <literal role="type">INTEGER</literal>, and the keywords
+ <literal role="type">DEC</literal> and <literal>FIXED</literal>
+ are synonyms for <literal role="type">DECIMAL</literal>. MySQL
+ treats <literal role="type">DOUBLE</literal> as a synonym for
<literal role="type">DOUBLE PRECISION</literal> (a nonstandard
extension). MySQL also treats <literal role="type">REAL</literal>
as a synonym for <literal role="type">DOUBLE PRECISION</literal>
Modified: trunk/refman-5.0/functions-core.xml
===================================================================
--- trunk/refman-5.0/functions-core.xml 2010-10-15 15:15:18 UTC (rev 23158)
+++ trunk/refman-5.0/functions-core.xml 2010-10-15 16:21:16 UTC (rev 23159)
Changed blocks: 2, Lines Added: 5, Lines Deleted: 6; 1230 bytes
@@ -5778,12 +5778,11 @@
<listitem>
<para>
- If one of the operands is an unsigned integer, and the other
- operand is also an integer, the result is an unsigned
- integer. For subtraction, if the
+ If both operands are integers and any of them are unsigned,
+ the result is an unsigned integer. For subtraction, if the
<literal role="sqlmode">NO_UNSIGNED_SUBTRACTION</literal>
- SQL mode is enabled, the subtraction result is signed even
- if any operand is unsigned.
+ SQL mode is enabled, the result is signed even if any
+ operand is unsigned.
</para>
</listitem>
@@ -5834,7 +5833,7 @@
<para>
For information about handling of overflow in numeric expression
- evaluation, see <xref linkend="numeric-types"/>.
+ evaluation, see <xref linkend="out-of-range-and-overflow"/>.
</para>
<para>
Modified: trunk/refman-5.0/precision-math.xml
===================================================================
--- trunk/refman-5.0/precision-math.xml 2010-10-15 15:15:18 UTC (rev 23158)
+++ trunk/refman-5.0/precision-math.xml 2010-10-15 16:21:16 UTC (rev 23159)
Changed blocks: 11, Lines Added: 38, Lines Deleted: 65; 8677 bytes
@@ -84,20 +84,22 @@
</itemizedlist>
<para>
- These changes have several implications for numeric operations:
+ These changes result in the following characteristics for numeric
+ operations and provide improved compliance with standard SQL:
</para>
<itemizedlist>
<listitem>
<para>
- <emphasis role="bold">More precise calculations</emphasis>: For
+ <emphasis role="bold">Precise calculations</emphasis>: For
exact-value numbers, calculations do not introduce
floating-point errors. Instead, exact precision is used. For
- example, a number such as <literal>.0001</literal> is treated as
- an exact value rather than as an approximation, and summing it
- 10,000 times produces a result of exactly <literal>1</literal>,
- not a value that merely <quote>close</quote> to 1.
+ example, MySQL treats a number such as <literal>.0001</literal>
+ as an exact value rather than as an approximation, and summing
+ it 10,000 times produces a result of exactly
+ <literal>1</literal>, not a value that is merely
+ <quote>close</quote> to 1.
</para>
</listitem>
@@ -113,7 +115,7 @@
<listitem>
<para>
- <emphasis role="bold">Improved platform independence</emphasis>:
+ <emphasis role="bold">Platform independence</emphasis>:
Operations on exact numeric values are the same across different
platforms such as Windows and Unix.
</para>
@@ -129,26 +131,19 @@
type. Similarly, you can treat division by zero as an error
rather than as an operation that produces a result of
<literal>NULL</literal>. The choice of which approach to take is
- determined by the setting of the
- <literal role="sysvar">sql_mode</literal> system variable.
+ determined by the setting of the server SQL mode.
</para>
</listitem>
</itemizedlist>
<para>
- An important result of these changes is that MySQL provides improved
- compliance with standard SQL.
- </para>
-
- <para>
The following discussion covers several aspects of how precision
- math works (including possible incompatibilities with older
- applications). At the end, some examples are given that demonstrate
+ math works, including possible incompatibilities with older
+ applications. At the end, some examples are given that demonstrate
how MySQL ¤t-series; handles numeric operations precisely. For
- information about using the
- <literal role="sysvar">sql_mode</literal> system variable to control
- the SQL mode, see <xref linkend="server-sql-mode"/>.
+ information about controlling the SQL mode, see
+ <xref linkend="server-sql-mode"/>.
</para>
<section id="precision-math-numbers">
@@ -159,8 +154,8 @@
The scope of precision math for exact-value operations includes
the exact-value data types (<literal role="type">DECIMAL</literal>
and integer types) and exact-value numeric literals.
- Approximate-value data types and numeric literals still are
- handled as floating-point numbers.
+ Approximate-value data types and numeric literals are handled as
+ floating-point numbers.
</para>
<para>
@@ -180,11 +175,10 @@
</para>
<para>
- Two numbers that look similar need not be both exact-value or both
- approximate-value. For example, <literal>2.34</literal> is an
- exact-value (fixed-point) number, whereas
- <literal>2.34E0</literal> is an approximate-value (floating-point)
- number.
+ Two numbers that look similar may be treated differently. For
+ example, <literal>2.34</literal> is an exact-value (fixed-point)
+ number, whereas <literal>2.34E0</literal> is an approximate-value
+ (floating-point) number.
</para>
<para>
@@ -251,9 +245,9 @@
</itemizedlist>
<para>
- Some of these changes result in possible incompatibilities for
- applications that are written for older versions of MySQL. These
- incompatibilities are noted throughout this section.
+ Some of these characteristics result in possible incompatibilities
+ for applications that are written for older versions of MySQL.
+ These incompatibilities are noted throughout this section.
</para>
<para>
@@ -292,7 +286,7 @@
that calculations on <literal role="type">DECIMAL</literal> values
are accurate up to 65 digits. This limit of 65 digits of precision
also applies to exact-value numeric literals, so the maximum range
- of such literals is different from before. (Prior to MySQL 5.0.3,
+ of such literals differs from before. (Prior to MySQL 5.0.3,
decimal values could have up to 254 digits. However, calculations
were done using floating-point and thus were approximate, not
exact.) This change in the range of literal values is another
@@ -301,16 +295,15 @@
<para>
Values for <literal role="type">DECIMAL</literal> columns no
- longer are represented as strings that require one byte per digit
- or sign character. Instead, a binary format is used that packs
- nine decimal digits into four bytes. This change to
+ longer are represented as strings that require 1 byte per digit or
+ sign character. Instead, a binary format is used that packs nine
+ decimal digits into 4 bytes. This change to
<literal role="type">DECIMAL</literal> storage format changes the
storage requirements as well. The storage requirements for the
integer and fractional parts of each value are determined
- separately. Each multiple of nine digits requires four bytes, and
- any remaining digits left over require some fraction of four
- bytes. The storage required for remaining digits is given by the
- following table.
+ separately. Each multiple of nine digits requires 4 bytes, and any
+ remaining digits require some fraction of 4 bytes. The storage
+ required for remaining digits is given by the following table.
</para>
<informaltable>
@@ -327,41 +320,21 @@
<entry>0</entry>
</row>
<row>
+ <entry>1–2</entry>
<entry>1</entry>
- <entry>1</entry>
</row>
<row>
+ <entry>3–4</entry>
<entry>2</entry>
- <entry>1</entry>
</row>
<row>
+ <entry>5–6</entry>
<entry>3</entry>
- <entry>2</entry>
</row>
<row>
+ <entry>7–9</entry>
<entry>4</entry>
- <entry>2</entry>
</row>
- <row>
- <entry>5</entry>
- <entry>3</entry>
- </row>
- <row>
- <entry>6</entry>
- <entry>3</entry>
- </row>
- <row>
- <entry>7</entry>
- <entry>4</entry>
- </row>
- <row>
- <entry>8</entry>
- <entry>4</entry>
- </row>
- <row>
- <entry>9</entry>
- <entry>4</entry>
- </row>
</tbody>
</tgroup>
</informaltable>
@@ -369,11 +342,11 @@
<para>
For example, a <literal>DECIMAL(18,9)</literal> column has nine
digits on either side of the decimal point, so the integer part
- and the fractional part each require four bytes. A
+ and the fractional part each require 4 bytes. A
<literal>DECIMAL(20,6)</literal> column has fourteen integer
digits and six fractional digits. The integer digits require four
- bytes for nine of the digits and three bytes for the remaining
- five digits. The six fractional digits require three bytes.
+ bytes for nine of the digits and 3 bytes for the remaining five
+ digits. The six fractional digits require 3 bytes.
</para>
<para>
@@ -395,7 +368,7 @@
The change of storage format also means that
<literal role="type">DECIMAL</literal> columns no longer support
the nonstandard extension that permitted values larger than the
- range implied by the column definition. Formerly, one byte was
+ range implied by the column definition. Formerly, 1 byte was
allocated for storing the sign character. For positive values that
needed no sign byte, MySQL permitted an extra digit to be stored
instead. For example, a <literal>DECIMAL(3,0)</literal> column
Modified: trunk/refman-5.1/data-types.xml
===================================================================
--- trunk/refman-5.1/data-types.xml 2010-10-15 15:15:18 UTC (rev 23158)
+++ trunk/refman-5.1/data-types.xml 2010-10-15 16:21:16 UTC (rev 23159)
Changed blocks: 1, Lines Added: 4, Lines Deleted: 4; 1168 bytes
@@ -2231,10 +2231,10 @@
<literal role="type">REAL</literal>, and
<literal role="type">DOUBLE PRECISION</literal>). The keyword
<literal role="type">INT</literal> is a synonym for
- <literal role="type">INTEGER</literal>, and the keyword
- <literal role="type">DEC</literal> is a synonym for
- <literal role="type">DECIMAL</literal>. MySQL treats
- <literal role="type">DOUBLE</literal> as a synonym for
+ <literal role="type">INTEGER</literal>, and the keywords
+ <literal role="type">DEC</literal> and <literal>FIXED</literal>
+ are synonyms for <literal role="type">DECIMAL</literal>. MySQL
+ treats <literal role="type">DOUBLE</literal> as a synonym for
<literal role="type">DOUBLE PRECISION</literal> (a nonstandard
extension). MySQL also treats <literal role="type">REAL</literal>
as a synonym for <literal role="type">DOUBLE PRECISION</literal>
Modified: trunk/refman-5.1/functions-core.xml
===================================================================
--- trunk/refman-5.1/functions-core.xml 2010-10-15 15:15:18 UTC (rev 23158)
+++ trunk/refman-5.1/functions-core.xml 2010-10-15 16:21:16 UTC (rev 23159)
Changed blocks: 2, Lines Added: 5, Lines Deleted: 6; 1230 bytes
@@ -5707,12 +5707,11 @@
<listitem>
<para>
- If one of the operands is an unsigned integer, and the other
- operand is also an integer, the result is an unsigned
- integer. For subtraction, if the
+ If both operands are integers and any of them are unsigned,
+ the result is an unsigned integer. For subtraction, if the
<literal role="sqlmode">NO_UNSIGNED_SUBTRACTION</literal>
- SQL mode is enabled, the subtraction result is signed even
- if any operand is unsigned.
+ SQL mode is enabled, the result is signed even if any
+ operand is unsigned.
</para>
</listitem>
@@ -5763,7 +5762,7 @@
<para>
For information about handling of overflow in numeric expression
- evaluation, see <xref linkend="numeric-types"/>.
+ evaluation, see <xref linkend="out-of-range-and-overflow"/>.
</para>
<para>
Modified: trunk/refman-5.1/precision-math.xml
===================================================================
--- trunk/refman-5.1/precision-math.xml 2010-10-15 15:15:18 UTC (rev 23158)
+++ trunk/refman-5.1/precision-math.xml 2010-10-15 16:21:16 UTC (rev 23159)
Changed blocks: 8, Lines Added: 34, Lines Deleted: 60; 7062 bytes
@@ -83,7 +83,8 @@
</itemizedlist>
<para>
- These features have several implications for numeric operations:
+ These features have several implications for numeric operations and
+ provide a high degree of compliance with standard SQL:
</para>
<itemizedlist>
@@ -93,10 +94,11 @@
<emphasis role="bold">Precise calculations</emphasis>: For
exact-value numbers, calculations do not introduce
floating-point errors. Instead, exact precision is used. For
- example, a number such as <literal>.0001</literal> is treated as
- an exact value rather than as an approximation, and summing it
- 10,000 times produces a result of exactly <literal>1</literal>,
- not a value that merely <quote>close</quote> to 1.
+ example, MySQL treats a number such as <literal>.0001</literal>
+ as an exact value rather than as an approximation, and summing
+ it 10,000 times produces a result of exactly
+ <literal>1</literal>, not a value that is merely
+ <quote>close</quote> to 1.
</para>
</listitem>
@@ -128,26 +130,19 @@
type. Similarly, you can treat division by zero as an error
rather than as an operation that produces a result of
<literal>NULL</literal>. The choice of which approach to take is
- determined by the setting of the
- <literal role="sysvar">sql_mode</literal> system variable.
+ determined by the setting of the server SQL mode.
</para>
</listitem>
</itemizedlist>
<para>
- An important result of these features is that MySQL ¤t-series;
- provides a high degree of compliance with standard SQL.
- </para>
-
- <para>
The following discussion covers several aspects of how precision
- math works (including possible incompatibilities with older
- applications). At the end, some examples are given that demonstrate
+ math works, including possible incompatibilities with older
+ applications. At the end, some examples are given that demonstrate
how MySQL ¤t-series; handles numeric operations precisely. For
- information about using the
- <literal role="sysvar">sql_mode</literal> system variable to control
- the SQL mode, see <xref linkend="server-sql-mode"/>.
+ information about controlling the SQL mode, see
+ <xref linkend="server-sql-mode"/>.
</para>
<section id="precision-math-numbers">
@@ -158,8 +153,8 @@
The scope of precision math for exact-value operations includes
the exact-value data types (<literal role="type">DECIMAL</literal>
and integer types) and exact-value numeric literals.
- Approximate-value data types and numeric literals still are
- handled as floating-point numbers.
+ Approximate-value data types and numeric literals are handled as
+ floating-point numbers.
</para>
<para>
@@ -179,11 +174,10 @@
</para>
<para>
- Two numbers that look similar need not be both exact-value or both
- approximate-value. For example, <literal>2.34</literal> is an
- exact-value (fixed-point) number, whereas
- <literal>2.34E0</literal> is an approximate-value (floating-point)
- number.
+ Two numbers that look similar may be treated differently. For
+ example, <literal>2.34</literal> is an exact-value (fixed-point)
+ number, whereas <literal>2.34E0</literal> is an approximate-value
+ (floating-point) number.
</para>
<para>
@@ -287,21 +281,21 @@
that calculations on <literal role="type">DECIMAL</literal> values
are accurate up to 65 digits. This limit of 65 digits of precision
also applies to exact-value numeric literals, so the maximum range
- of such literals is different from before. (In older versions of
- MySQL, decimal values could have up to 254 digits. However,
- calculations were done using floating-point and thus were
- approximate, not exact.)
+ of such literals differs from before. (In older versions of MySQL,
+ decimal values could have up to 254 digits. However, calculations
+ were done using floating-point and thus were approximate, not
+ exact.)
</para>
<para>
Values for <literal role="type">DECIMAL</literal> columns in MySQL
¤t-series; are stored using a binary format that packs nine
- decimal digits into four bytes. The storage requirements for the
+ decimal digits into 4 bytes. The storage requirements for the
integer and fractional parts of each value are determined
- separately. Each multiple of nine digits requires four bytes, and
- any remaining digits left over require some fraction of four
- bytes. The storage required for remaining digits is given by the
- following table.
+ separately. Each multiple of nine digits requires 4 bytes, and any
+ remaining digits left over require some fraction of 4 bytes. The
+ storage required for remaining digits is given by the following
+ table.
</para>
<informaltable>
@@ -318,41 +312,21 @@
<entry>0</entry>
</row>
<row>
+ <entry>1–2</entry>
<entry>1</entry>
- <entry>1</entry>
</row>
<row>
+ <entry>3–4</entry>
<entry>2</entry>
- <entry>1</entry>
</row>
<row>
+ <entry>5–6</entry>
<entry>3</entry>
- <entry>2</entry>
</row>
<row>
+ <entry>7–9</entry>
<entry>4</entry>
- <entry>2</entry>
</row>
- <row>
- <entry>5</entry>
- <entry>3</entry>
- </row>
- <row>
- <entry>6</entry>
- <entry>3</entry>
- </row>
- <row>
- <entry>7</entry>
- <entry>4</entry>
- </row>
- <row>
- <entry>8</entry>
- <entry>4</entry>
- </row>
- <row>
- <entry>9</entry>
- <entry>4</entry>
- </row>
</tbody>
</tgroup>
</informaltable>
@@ -360,11 +334,11 @@
<para>
For example, a <literal>DECIMAL(18,9)</literal> column has nine
digits on either side of the decimal point, so the integer part
- and the fractional part each require four bytes. A
+ and the fractional part each require 4 bytes. A
<literal>DECIMAL(20,6)</literal> column has fourteen integer
digits and six fractional digits. The integer digits require four
- bytes for nine of the digits and three bytes for the remaining
- five digits. The six fractional digits require three bytes.
+ bytes for nine of the digits and 3 bytes for the remaining five
+ digits. The six fractional digits require 3 bytes.
</para>
<para>
Modified: trunk/refman-5.5/data-types.xml
===================================================================
--- trunk/refman-5.5/data-types.xml 2010-10-15 15:15:18 UTC (rev 23158)
+++ trunk/refman-5.5/data-types.xml 2010-10-15 16:21:16 UTC (rev 23159)
Changed blocks: 1, Lines Added: 4, Lines Deleted: 4; 1168 bytes
@@ -2231,10 +2231,10 @@
<literal role="type">REAL</literal>, and
<literal role="type">DOUBLE PRECISION</literal>). The keyword
<literal role="type">INT</literal> is a synonym for
- <literal role="type">INTEGER</literal>, and the keyword
- <literal role="type">DEC</literal> is a synonym for
- <literal role="type">DECIMAL</literal>. MySQL treats
- <literal role="type">DOUBLE</literal> as a synonym for
+ <literal role="type">INTEGER</literal>, and the keywords
+ <literal role="type">DEC</literal> and <literal>FIXED</literal>
+ are synonyms for <literal role="type">DECIMAL</literal>. MySQL
+ treats <literal role="type">DOUBLE</literal> as a synonym for
<literal role="type">DOUBLE PRECISION</literal> (a nonstandard
extension). MySQL also treats <literal role="type">REAL</literal>
as a synonym for <literal role="type">DOUBLE PRECISION</literal>
Modified: trunk/refman-5.5/functions-core.xml
===================================================================
--- trunk/refman-5.5/functions-core.xml 2010-10-15 15:15:18 UTC (rev 23158)
+++ trunk/refman-5.5/functions-core.xml 2010-10-15 16:21:16 UTC (rev 23159)
Changed blocks: 2, Lines Added: 5, Lines Deleted: 6; 1230 bytes
@@ -5889,12 +5889,11 @@
<listitem>
<para>
- If one of the operands is an unsigned integer, and the other
- operand is also an integer, the result is an unsigned
- integer. For subtraction, if the
+ If both operands are integers and any of them are unsigned,
+ the result is an unsigned integer. For subtraction, if the
<literal role="sqlmode">NO_UNSIGNED_SUBTRACTION</literal>
- SQL mode is enabled, the subtraction result is signed even
- if any operand is unsigned.
+ SQL mode is enabled, the result is signed even if any
+ operand is unsigned.
</para>
</listitem>
@@ -5945,7 +5944,7 @@
<para>
For information about handling of overflow in numeric expression
- evaluation, see <xref linkend="numeric-types"/>.
+ evaluation, see <xref linkend="out-of-range-and-overflow"/>.
</para>
<para>
Modified: trunk/refman-5.5/precision-math.xml
===================================================================
--- trunk/refman-5.5/precision-math.xml 2010-10-15 15:15:18 UTC (rev 23158)
+++ trunk/refman-5.5/precision-math.xml 2010-10-15 16:21:16 UTC (rev 23159)
Changed blocks: 8, Lines Added: 34, Lines Deleted: 60; 7062 bytes
@@ -83,7 +83,8 @@
</itemizedlist>
<para>
- These features have several implications for numeric operations:
+ These features have several implications for numeric operations and
+ provide a high degree of compliance with standard SQL:
</para>
<itemizedlist>
@@ -93,10 +94,11 @@
<emphasis role="bold">Precise calculations</emphasis>: For
exact-value numbers, calculations do not introduce
floating-point errors. Instead, exact precision is used. For
- example, a number such as <literal>.0001</literal> is treated as
- an exact value rather than as an approximation, and summing it
- 10,000 times produces a result of exactly <literal>1</literal>,
- not a value that merely <quote>close</quote> to 1.
+ example, MySQL treats a number such as <literal>.0001</literal>
+ as an exact value rather than as an approximation, and summing
+ it 10,000 times produces a result of exactly
+ <literal>1</literal>, not a value that is merely
+ <quote>close</quote> to 1.
</para>
</listitem>
@@ -128,26 +130,19 @@
type. Similarly, you can treat division by zero as an error
rather than as an operation that produces a result of
<literal>NULL</literal>. The choice of which approach to take is
- determined by the setting of the
- <literal role="sysvar">sql_mode</literal> system variable.
+ determined by the setting of the server SQL mode.
</para>
</listitem>
</itemizedlist>
<para>
- An important result of these features is that MySQL ¤t-series;
- provides a high degree of compliance with standard SQL.
- </para>
-
- <para>
The following discussion covers several aspects of how precision
- math works (including possible incompatibilities with older
- applications). At the end, some examples are given that demonstrate
+ math works, including possible incompatibilities with older
+ applications. At the end, some examples are given that demonstrate
how MySQL ¤t-series; handles numeric operations precisely. For
- information about using the
- <literal role="sysvar">sql_mode</literal> system variable to control
- the SQL mode, see <xref linkend="server-sql-mode"/>.
+ information about controlling the SQL mode, see
+ <xref linkend="server-sql-mode"/>.
</para>
<section id="precision-math-numbers">
@@ -158,8 +153,8 @@
The scope of precision math for exact-value operations includes
the exact-value data types (<literal role="type">DECIMAL</literal>
and integer types) and exact-value numeric literals.
- Approximate-value data types and numeric literals still are
- handled as floating-point numbers.
+ Approximate-value data types and numeric literals are handled as
+ floating-point numbers.
</para>
<para>
@@ -179,11 +174,10 @@
</para>
<para>
- Two numbers that look similar need not be both exact-value or both
- approximate-value. For example, <literal>2.34</literal> is an
- exact-value (fixed-point) number, whereas
- <literal>2.34E0</literal> is an approximate-value (floating-point)
- number.
+ Two numbers that look similar may be treated differently. For
+ example, <literal>2.34</literal> is an exact-value (fixed-point)
+ number, whereas <literal>2.34E0</literal> is an approximate-value
+ (floating-point) number.
</para>
<para>
@@ -287,21 +281,21 @@
that calculations on <literal role="type">DECIMAL</literal> values
are accurate up to 65 digits. This limit of 65 digits of precision
also applies to exact-value numeric literals, so the maximum range
- of such literals is different from before. (In older versions of
- MySQL, decimal values could have up to 254 digits. However,
- calculations were done using floating-point and thus were
- approximate, not exact.)
+ of such literals differs from before. (In older versions of MySQL,
+ decimal values could have up to 254 digits. However, calculations
+ were done using floating-point and thus were approximate, not
+ exact.)
</para>
<para>
Values for <literal role="type">DECIMAL</literal> columns in MySQL
¤t-series; are stored using a binary format that packs nine
- decimal digits into four bytes. The storage requirements for the
+ decimal digits into 4 bytes. The storage requirements for the
integer and fractional parts of each value are determined
- separately. Each multiple of nine digits requires four bytes, and
- any remaining digits left over require some fraction of four
- bytes. The storage required for remaining digits is given by the
- following table.
+ separately. Each multiple of nine digits requires 4 bytes, and any
+ remaining digits left over require some fraction of 4 bytes. The
+ storage required for remaining digits is given by the following
+ table.
</para>
<informaltable>
@@ -318,41 +312,21 @@
<entry>0</entry>
</row>
<row>
+ <entry>1–2</entry>
<entry>1</entry>
- <entry>1</entry>
</row>
<row>
+ <entry>3–4</entry>
<entry>2</entry>
- <entry>1</entry>
</row>
<row>
+ <entry>5–6</entry>
<entry>3</entry>
- <entry>2</entry>
</row>
<row>
+ <entry>7–9</entry>
<entry>4</entry>
- <entry>2</entry>
</row>
- <row>
- <entry>5</entry>
- <entry>3</entry>
- </row>
- <row>
- <entry>6</entry>
- <entry>3</entry>
- </row>
- <row>
- <entry>7</entry>
- <entry>4</entry>
- </row>
- <row>
- <entry>8</entry>
- <entry>4</entry>
- </row>
- <row>
- <entry>9</entry>
- <entry>4</entry>
- </row>
</tbody>
</tgroup>
</informaltable>
@@ -360,11 +334,11 @@
<para>
For example, a <literal>DECIMAL(18,9)</literal> column has nine
digits on either side of the decimal point, so the integer part
- and the fractional part each require four bytes. A
+ and the fractional part each require 4 bytes. A
<literal>DECIMAL(20,6)</literal> column has fourteen integer
digits and six fractional digits. The integer digits require four
- bytes for nine of the digits and three bytes for the remaining
- five digits. The six fractional digits require three bytes.
+ bytes for nine of the digits and 3 bytes for the remaining five
+ digits. The six fractional digits require 3 bytes.
</para>
<para>
Modified: trunk/refman-5.6/data-types.xml
===================================================================
--- trunk/refman-5.6/data-types.xml 2010-10-15 15:15:18 UTC (rev 23158)
+++ trunk/refman-5.6/data-types.xml 2010-10-15 16:21:16 UTC (rev 23159)
Changed blocks: 1, Lines Added: 4, Lines Deleted: 4; 1168 bytes
@@ -2231,10 +2231,10 @@
<literal role="type">REAL</literal>, and
<literal role="type">DOUBLE PRECISION</literal>). The keyword
<literal role="type">INT</literal> is a synonym for
- <literal role="type">INTEGER</literal>, and the keyword
- <literal role="type">DEC</literal> is a synonym for
- <literal role="type">DECIMAL</literal>. MySQL treats
- <literal role="type">DOUBLE</literal> as a synonym for
+ <literal role="type">INTEGER</literal>, and the keywords
+ <literal role="type">DEC</literal> and <literal>FIXED</literal>
+ are synonyms for <literal role="type">DECIMAL</literal>. MySQL
+ treats <literal role="type">DOUBLE</literal> as a synonym for
<literal role="type">DOUBLE PRECISION</literal> (a nonstandard
extension). MySQL also treats <literal role="type">REAL</literal>
as a synonym for <literal role="type">DOUBLE PRECISION</literal>
Modified: trunk/refman-5.6/functions-core.xml
===================================================================
--- trunk/refman-5.6/functions-core.xml 2010-10-15 15:15:18 UTC (rev 23158)
+++ trunk/refman-5.6/functions-core.xml 2010-10-15 16:21:16 UTC (rev 23159)
Changed blocks: 2, Lines Added: 5, Lines Deleted: 6; 1230 bytes
@@ -6174,12 +6174,11 @@
<listitem>
<para>
- If one of the operands is an unsigned integer, and the other
- operand is also an integer, the result is an unsigned
- integer. For subtraction, if the
+ If both operands are integers and any of them are unsigned,
+ the result is an unsigned integer. For subtraction, if the
<literal role="sqlmode">NO_UNSIGNED_SUBTRACTION</literal>
- SQL mode is enabled, the subtraction result is signed even
- if any operand is unsigned.
+ SQL mode is enabled, the result is signed even if any
+ operand is unsigned.
</para>
</listitem>
@@ -6230,7 +6229,7 @@
<para>
For information about handling of overflow in numeric expression
- evaluation, see <xref linkend="numeric-types"/>.
+ evaluation, see <xref linkend="out-of-range-and-overflow"/>.
</para>
<para>
Modified: trunk/refman-5.6/precision-math.xml
===================================================================
--- trunk/refman-5.6/precision-math.xml 2010-10-15 15:15:18 UTC (rev 23158)
+++ trunk/refman-5.6/precision-math.xml 2010-10-15 16:21:16 UTC (rev 23159)
Changed blocks: 8, Lines Added: 34, Lines Deleted: 60; 7062 bytes
@@ -83,7 +83,8 @@
</itemizedlist>
<para>
- These features have several implications for numeric operations:
+ These features have several implications for numeric operations and
+ provide a high degree of compliance with standard SQL:
</para>
<itemizedlist>
@@ -93,10 +94,11 @@
<emphasis role="bold">Precise calculations</emphasis>: For
exact-value numbers, calculations do not introduce
floating-point errors. Instead, exact precision is used. For
- example, a number such as <literal>.0001</literal> is treated as
- an exact value rather than as an approximation, and summing it
- 10,000 times produces a result of exactly <literal>1</literal>,
- not a value that merely <quote>close</quote> to 1.
+ example, MySQL treats a number such as <literal>.0001</literal>
+ as an exact value rather than as an approximation, and summing
+ it 10,000 times produces a result of exactly
+ <literal>1</literal>, not a value that is merely
+ <quote>close</quote> to 1.
</para>
</listitem>
@@ -128,26 +130,19 @@
type. Similarly, you can treat division by zero as an error
rather than as an operation that produces a result of
<literal>NULL</literal>. The choice of which approach to take is
- determined by the setting of the
- <literal role="sysvar">sql_mode</literal> system variable.
+ determined by the setting of the server SQL mode.
</para>
</listitem>
</itemizedlist>
<para>
- An important result of these features is that MySQL ¤t-series;
- provides a high degree of compliance with standard SQL.
- </para>
-
- <para>
The following discussion covers several aspects of how precision
- math works (including possible incompatibilities with older
- applications). At the end, some examples are given that demonstrate
+ math works, including possible incompatibilities with older
+ applications. At the end, some examples are given that demonstrate
how MySQL ¤t-series; handles numeric operations precisely. For
- information about using the
- <literal role="sysvar">sql_mode</literal> system variable to control
- the SQL mode, see <xref linkend="server-sql-mode"/>.
+ information about controlling the SQL mode, see
+ <xref linkend="server-sql-mode"/>.
</para>
<section id="precision-math-numbers">
@@ -158,8 +153,8 @@
The scope of precision math for exact-value operations includes
the exact-value data types (<literal role="type">DECIMAL</literal>
and integer types) and exact-value numeric literals.
- Approximate-value data types and numeric literals still are
- handled as floating-point numbers.
+ Approximate-value data types and numeric literals are handled as
+ floating-point numbers.
</para>
<para>
@@ -179,11 +174,10 @@
</para>
<para>
- Two numbers that look similar need not be both exact-value or both
- approximate-value. For example, <literal>2.34</literal> is an
- exact-value (fixed-point) number, whereas
- <literal>2.34E0</literal> is an approximate-value (floating-point)
- number.
+ Two numbers that look similar may be treated differently. For
+ example, <literal>2.34</literal> is an exact-value (fixed-point)
+ number, whereas <literal>2.34E0</literal> is an approximate-value
+ (floating-point) number.
</para>
<para>
@@ -287,21 +281,21 @@
that calculations on <literal role="type">DECIMAL</literal> values
are accurate up to 65 digits. This limit of 65 digits of precision
also applies to exact-value numeric literals, so the maximum range
- of such literals is different from before. (In older versions of
- MySQL, decimal values could have up to 254 digits. However,
- calculations were done using floating-point and thus were
- approximate, not exact.)
+ of such literals differs from before. (In older versions of MySQL,
+ decimal values could have up to 254 digits. However, calculations
+ were done using floating-point and thus were approximate, not
+ exact.)
</para>
<para>
Values for <literal role="type">DECIMAL</literal> columns in MySQL
¤t-series; are stored using a binary format that packs nine
- decimal digits into four bytes. The storage requirements for the
+ decimal digits into 4 bytes. The storage requirements for the
integer and fractional parts of each value are determined
- separately. Each multiple of nine digits requires four bytes, and
- any remaining digits left over require some fraction of four
- bytes. The storage required for remaining digits is given by the
- following table.
+ separately. Each multiple of nine digits requires 4 bytes, and any
+ remaining digits left over require some fraction of 4 bytes. The
+ storage required for remaining digits is given by the following
+ table.
</para>
<informaltable>
@@ -318,41 +312,21 @@
<entry>0</entry>
</row>
<row>
+ <entry>1–2</entry>
<entry>1</entry>
- <entry>1</entry>
</row>
<row>
+ <entry>3–4</entry>
<entry>2</entry>
- <entry>1</entry>
</row>
<row>
+ <entry>5–6</entry>
<entry>3</entry>
- <entry>2</entry>
</row>
<row>
+ <entry>7–9</entry>
<entry>4</entry>
- <entry>2</entry>
</row>
- <row>
- <entry>5</entry>
- <entry>3</entry>
- </row>
- <row>
- <entry>6</entry>
- <entry>3</entry>
- </row>
- <row>
- <entry>7</entry>
- <entry>4</entry>
- </row>
- <row>
- <entry>8</entry>
- <entry>4</entry>
- </row>
- <row>
- <entry>9</entry>
- <entry>4</entry>
- </row>
</tbody>
</tgroup>
</informaltable>
@@ -360,11 +334,11 @@
<para>
For example, a <literal>DECIMAL(18,9)</literal> column has nine
digits on either side of the decimal point, so the integer part
- and the fractional part each require four bytes. A
+ and the fractional part each require 4 bytes. A
<literal>DECIMAL(20,6)</literal> column has fourteen integer
digits and six fractional digits. The integer digits require four
- bytes for nine of the digits and three bytes for the remaining
- five digits. The six fractional digits require three bytes.
+ bytes for nine of the digits and 3 bytes for the remaining five
+ digits. The six fractional digits require 3 bytes.
</para>
<para>
Modified: trunk/refman-6.0/data-types.xml
===================================================================
--- trunk/refman-6.0/data-types.xml 2010-10-15 15:15:18 UTC (rev 23158)
+++ trunk/refman-6.0/data-types.xml 2010-10-15 16:21:16 UTC (rev 23159)
Changed blocks: 1, Lines Added: 4, Lines Deleted: 4; 1168 bytes
@@ -2231,10 +2231,10 @@
<literal role="type">REAL</literal>, and
<literal role="type">DOUBLE PRECISION</literal>). The keyword
<literal role="type">INT</literal> is a synonym for
- <literal role="type">INTEGER</literal>, and the keyword
- <literal role="type">DEC</literal> is a synonym for
- <literal role="type">DECIMAL</literal>. MySQL treats
- <literal role="type">DOUBLE</literal> as a synonym for
+ <literal role="type">INTEGER</literal>, and the keywords
+ <literal role="type">DEC</literal> and <literal>FIXED</literal>
+ are synonyms for <literal role="type">DECIMAL</literal>. MySQL
+ treats <literal role="type">DOUBLE</literal> as a synonym for
<literal role="type">DOUBLE PRECISION</literal> (a nonstandard
extension). MySQL also treats <literal role="type">REAL</literal>
as a synonym for <literal role="type">DOUBLE PRECISION</literal>
Modified: trunk/refman-6.0/functions-core.xml
===================================================================
--- trunk/refman-6.0/functions-core.xml 2010-10-15 15:15:18 UTC (rev 23158)
+++ trunk/refman-6.0/functions-core.xml 2010-10-15 16:21:16 UTC (rev 23159)
Changed blocks: 2, Lines Added: 5, Lines Deleted: 6; 1230 bytes
@@ -6216,12 +6216,11 @@
<listitem>
<para>
- If one of the operands is an unsigned integer, and the other
- operand is also an integer, the result is an unsigned
- integer. For subtraction, if the
+ If both operands are integers and any of them are unsigned,
+ the result is an unsigned integer. For subtraction, if the
<literal role="sqlmode">NO_UNSIGNED_SUBTRACTION</literal>
- SQL mode is enabled, the subtraction result is signed even
- if any operand is unsigned.
+ SQL mode is enabled, the result is signed even if any
+ operand is unsigned.
</para>
</listitem>
@@ -6272,7 +6271,7 @@
<para>
For information about handling of overflow in numeric expression
- evaluation, see <xref linkend="numeric-types"/>.
+ evaluation, see <xref linkend="out-of-range-and-overflow"/>.
</para>
<para>
Modified: trunk/refman-6.0/precision-math.xml
===================================================================
--- trunk/refman-6.0/precision-math.xml 2010-10-15 15:15:18 UTC (rev 23158)
+++ trunk/refman-6.0/precision-math.xml 2010-10-15 16:21:16 UTC (rev 23159)
Changed blocks: 8, Lines Added: 34, Lines Deleted: 60; 7062 bytes
@@ -83,7 +83,8 @@
</itemizedlist>
<para>
- These features have several implications for numeric operations:
+ These features have several implications for numeric operations and
+ provide a high degree of compliance with standard SQL:
</para>
<itemizedlist>
@@ -93,10 +94,11 @@
<emphasis role="bold">Precise calculations</emphasis>: For
exact-value numbers, calculations do not introduce
floating-point errors. Instead, exact precision is used. For
- example, a number such as <literal>.0001</literal> is treated as
- an exact value rather than as an approximation, and summing it
- 10,000 times produces a result of exactly <literal>1</literal>,
- not a value that merely <quote>close</quote> to 1.
+ example, MySQL treats a number such as <literal>.0001</literal>
+ as an exact value rather than as an approximation, and summing
+ it 10,000 times produces a result of exactly
+ <literal>1</literal>, not a value that is merely
+ <quote>close</quote> to 1.
</para>
</listitem>
@@ -128,26 +130,19 @@
type. Similarly, you can treat division by zero as an error
rather than as an operation that produces a result of
<literal>NULL</literal>. The choice of which approach to take is
- determined by the setting of the
- <literal role="sysvar">sql_mode</literal> system variable.
+ determined by the setting of the server SQL mode.
</para>
</listitem>
</itemizedlist>
<para>
- An important result of these features is that MySQL ¤t-series;
- provides a high degree of compliance with standard SQL.
- </para>
-
- <para>
The following discussion covers several aspects of how precision
- math works (including possible incompatibilities with older
- applications). At the end, some examples are given that demonstrate
+ math works, including possible incompatibilities with older
+ applications. At the end, some examples are given that demonstrate
how MySQL ¤t-series; handles numeric operations precisely. For
- information about using the
- <literal role="sysvar">sql_mode</literal> system variable to control
- the SQL mode, see <xref linkend="server-sql-mode"/>.
+ information about controlling the SQL mode, see
+ <xref linkend="server-sql-mode"/>.
</para>
<section id="precision-math-numbers">
@@ -158,8 +153,8 @@
The scope of precision math for exact-value operations includes
the exact-value data types (<literal role="type">DECIMAL</literal>
and integer types) and exact-value numeric literals.
- Approximate-value data types and numeric literals still are
- handled as floating-point numbers.
+ Approximate-value data types and numeric literals are handled as
+ floating-point numbers.
</para>
<para>
@@ -179,11 +174,10 @@
</para>
<para>
- Two numbers that look similar need not be both exact-value or both
- approximate-value. For example, <literal>2.34</literal> is an
- exact-value (fixed-point) number, whereas
- <literal>2.34E0</literal> is an approximate-value (floating-point)
- number.
+ Two numbers that look similar may be treated differently. For
+ example, <literal>2.34</literal> is an exact-value (fixed-point)
+ number, whereas <literal>2.34E0</literal> is an approximate-value
+ (floating-point) number.
</para>
<para>
@@ -287,21 +281,21 @@
that calculations on <literal role="type">DECIMAL</literal> values
are accurate up to 65 digits. This limit of 65 digits of precision
also applies to exact-value numeric literals, so the maximum range
- of such literals is different from before. (In older versions of
- MySQL, decimal values could have up to 254 digits. However,
- calculations were done using floating-point and thus were
- approximate, not exact.)
+ of such literals differs from before. (In older versions of MySQL,
+ decimal values could have up to 254 digits. However, calculations
+ were done using floating-point and thus were approximate, not
+ exact.)
</para>
<para>
Values for <literal role="type">DECIMAL</literal> columns in MySQL
¤t-series; are stored using a binary format that packs nine
- decimal digits into four bytes. The storage requirements for the
+ decimal digits into 4 bytes. The storage requirements for the
integer and fractional parts of each value are determined
- separately. Each multiple of nine digits requires four bytes, and
- any remaining digits left over require some fraction of four
- bytes. The storage required for remaining digits is given by the
- following table.
+ separately. Each multiple of nine digits requires 4 bytes, and any
+ remaining digits left over require some fraction of 4 bytes. The
+ storage required for remaining digits is given by the following
+ table.
</para>
<informaltable>
@@ -318,41 +312,21 @@
<entry>0</entry>
</row>
<row>
+ <entry>1–2</entry>
<entry>1</entry>
- <entry>1</entry>
</row>
<row>
+ <entry>3–4</entry>
<entry>2</entry>
- <entry>1</entry>
</row>
<row>
+ <entry>5–6</entry>
<entry>3</entry>
- <entry>2</entry>
</row>
<row>
+ <entry>7–9</entry>
<entry>4</entry>
- <entry>2</entry>
</row>
- <row>
- <entry>5</entry>
- <entry>3</entry>
- </row>
- <row>
- <entry>6</entry>
- <entry>3</entry>
- </row>
- <row>
- <entry>7</entry>
- <entry>4</entry>
- </row>
- <row>
- <entry>8</entry>
- <entry>4</entry>
- </row>
- <row>
- <entry>9</entry>
- <entry>4</entry>
- </row>
</tbody>
</tgroup>
</informaltable>
@@ -360,11 +334,11 @@
<para>
For example, a <literal>DECIMAL(18,9)</literal> column has nine
digits on either side of the decimal point, so the integer part
- and the fractional part each require four bytes. A
+ and the fractional part each require 4 bytes. A
<literal>DECIMAL(20,6)</literal> column has fourteen integer
digits and six fractional digits. The integer digits require four
- bytes for nine of the digits and three bytes for the remaining
- five digits. The six fractional digits require three bytes.
+ bytes for nine of the digits and 3 bytes for the remaining five
+ digits. The six fractional digits require 3 bytes.
</para>
<para>
| Thread |
|---|
| • svn commit - mysqldoc@docsrva: r23159 - in trunk: . refman-4.1 refman-5.0 refman-5.1 refman-5.5 refman-5.6 refman-6.0 | paul.dubois | 15 Oct |
