How Can I Convert Existing Primary Key IDs to Auto-Incrementers in MySQL?

Converting Primary Key IDs to Auto-Incrementers in MySQL

A database acquired from another developer may not have auto-incrementers enabled on its tables, despite having primary key IDs. This raises the question of whether these primary key IDs can be converted into auto-incrementers.

Solution

To convert existing primary key IDs into auto-incrementers, you can use the ALTER TABLE statement with the MODIFY COLUMN clause. This allows you to modify the column definition and specify the AUTO_INCREMENT option.

For example:

<code class="mysql">ALTER TABLE foo MODIFY COLUMN id INT NOT NULL AUTO_INCREMENT;</code>

Here, the foo table has a column named id that is not currently auto-incrementing. After executing the statement, the id column will be modified to use auto-increment.

Note:

• The original primary key constraint remains unaffected by this modification.
• You can verify the change by using the SHOW CREATE TABLE statement to display the updated table definition.
• When inserting new rows into the table, the id column will be automatically assigned a new value.

Troubleshooting

If you encounter an error such as "Error on rename of '.DBNAME#sql-6c8_62259c' to '.DBNAMEdealer_master_events'," it is likely due to conflicts with foreign key constraints. To diagnose and resolve the issue, refer to resources like:

• What does mysql error 1025 (HY000): Error on rename of '.foo' (errorno: 150) mean?
• http://www.simplicidade.org/notes/archives/2008/03/mysql_errno_150.html

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