GNU Info

Info Node: (mysql.info)Change column order

(mysql.info)Change column order


Next: Temporary table problems Prev: ALTER TABLE problems Up: Table Definition Issues
Enter node , (file) or (file)node

How To Change the Order of Columns in a Table
---------------------------------------------

The whole point of SQL is to abstract the application from the data
storage format.  You should always specify the order in which you wish
to retrieve your data.  For example:

     SELECT col_name1, col_name2, col_name3 FROM tbl_name;

will return columns in the order `col_name1', `col_name2', `col_name3',
whereas:

     SELECT col_name1, col_name3, col_name2 FROM tbl_name;

will return columns in the order `col_name1', `col_name3', `col_name2'.

You should *NEVER*, in an application, use `SELECT *' and retrieve the
columns based on their position, because the order in which columns are
returned *CANNOT* be guaranteed over time. A simple change to your
database may cause your application to fail rather dramatically.

If you want to change the order of columns anyway, you can do it as
follows:

  1. Create a new table with the columns in the right order.

  2. Execute `INSERT INTO new_table SELECT fields-in-new_table-order
     FROM old_table'.

  3. Drop or rename `old_table'.

  4. `ALTER TABLE new_table RENAME old_table'.


automatically generated by info2www version 1.2.2.9