From: Dan Nelson
Date: July 10 2002 3:33am
Subject: Re: Char type changes to Varchar type
List-Archive: http://lists.mysql.com/mysql/114154
Message-Id: <20020710033355.GE8625@dan.emsphone.com>
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In the last episode (Jul 09), Michael Ivanyo said:
> I am using MySql with InnoDB and have just discovered that tables
> created using char types show up as varchars when I type, describe
> tableName.  Previously, I was using MyIsam tables and did not see
> char types being changed to varchars so I am a bit puzzled.
> 
> This is true for almost all of the tables I've created, only a couple
> of tables retained the char type as specified in my create table
> script.
> 
> Is this documented behavior?  I haven't been using MySql very long
> and haven't seen it mentioned anywhere.

http://www.mysql.com/doc/S/i/Silent_column_changes.html

  * If any column in a table has a variable length, the entire row is
    variable-length as a result. Therefore, if a table contains any
    variable-length columns (VARCHAR, TEXT, or BLOB), all CHAR columns
    longer than three characters are changed to VARCHAR columns. This
    doesn't affect how you use the columns in any way; in MySQL,
    VARCHAR is just a different way to store characters. MySQL performs
    this conversion because it saves space and makes table operations
    faster. See section 7 MySQL Table Types.

-- 
	Dan Nelson
	dnelson@stripped