Insert auto increment primary key to existing table

mysql primary-key
FlyingCat picture FlyingCat · Jan 30, 2012 · Viewed 226.4k times · Source

I am trying to alter a table which has no primary key nor auto_increment column. I know how to add an primary key column but I was wondering if it's possible to insert data into the primary key column automatically (I already have 500 rows in DB and want to give them id but I don't want to do it manually). Any thoughts? Thanks a lot.

Answer

Michael Berkowski picture Michael Berkowski · Jan 30, 2012

An ALTER TABLE statement adding the PRIMARY KEY column works correctly in my testing:

ALTER TABLE tbl ADD id INT PRIMARY KEY AUTO_INCREMENT;

On a temporary table created for testing purposes, the above statement created the AUTO_INCREMENT id column and inserted auto-increment values for each existing row in the table, starting with 1.

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