bk commit into 5.0 tree (holyfoot:1.2602) BUG#31616

[holyfoot]

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ChangeSet@stripped, 2008-04-21 09:04:00+05:00, holyfoot@stripped +3 -0
  Bug #31616 div_precision_increment description looks wrong
  
  Item_func_div didn't calculate the precision of the result properly.
  The result of 5/0.0001 is 5000 so we have to add decimals of the divisor
  to the planned precision.

  mysql-test/r/type_newdecimal.result@stripped, 2008-04-21 09:03:58+05:00, holyfoot@stripped
+15 -0
    Bug #31616 div_precision_increment description looks wrong
    
    test result

  mysql-test/t/type_newdecimal.test@stripped, 2008-04-21 09:03:58+05:00, holyfoot@stripped
+10 -0
    Bug #31616 div_precision_increment description looks wrong
    
    test case

  sql/item_func.cc@stripped, 2008-04-21 09:03:58+05:00, holyfoot@stripped +2 -1
    Bug #31616 div_precision_increment description looks wrong
    
    precision must be increased with args[1]->decimals parameter

diff -Nrup a/mysql-test/r/type_newdecimal.result b/mysql-test/r/type_newdecimal.result
--- a/mysql-test/r/type_newdecimal.result	2007-11-17 22:05:29 +04:00
+++ b/mysql-test/r/type_newdecimal.result	2008-04-21 09:03:58 +05:00
@@ -1519,4 +1519,19 @@ SELECT f1 FROM t1;
 f1
 99999999999999999999999999999.999999999999999999999999999999
 DROP TABLE t1;
+create table t1 as select 5.05 / 0.014;
+Warnings:
+Note	1265	Data truncated for column '5.05 / 0.014' at row 1
+show warnings;
+Level	Code	Message
+Note	1265	Data truncated for column '5.05 / 0.014' at row 1
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `5.05 / 0.014` decimal(10,6) default NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+select * from t1;
+5.05 / 0.014
+360.714286
+DROP TABLE t1;
 End of 5.0 tests
diff -Nrup a/mysql-test/t/type_newdecimal.test b/mysql-test/t/type_newdecimal.test
--- a/mysql-test/t/type_newdecimal.test	2007-11-17 22:05:29 +04:00
+++ b/mysql-test/t/type_newdecimal.test	2008-04-21 09:03:58 +05:00
@@ -1216,4 +1216,14 @@ DESC t1;
 SELECT f1 FROM t1;
 DROP TABLE t1;
 
+#
+# Bug #31616 div_precision_increment description looks wrong 
+#
+
+create table t1 as select 5.05 / 0.014;
+show warnings;
+show create table t1;
+select * from t1;
+DROP TABLE t1;
+
 --echo End of 5.0 tests
diff -Nrup a/sql/item_func.cc b/sql/item_func.cc
--- a/sql/item_func.cc	2008-03-12 11:54:54 +04:00
+++ b/sql/item_func.cc	2008-04-21 09:03:58 +05:00
@@ -1315,7 +1315,8 @@ my_decimal *Item_func_div::decimal_op(my
 
 void Item_func_div::result_precision()
 {
-  uint precision=min(args[0]->decimal_precision() + prec_increment,
+  uint precision=min(args[0]->decimal_precision() + 
+                     args[1]->decimals + prec_increment,
                      DECIMAL_MAX_PRECISION);
   /* Integer operations keep unsigned_flag if one of arguments is unsigned */
   if (result_type() == INT_RESULT)