Question

I figure this is very easy, but I am trying to run this command only if those columns already don’t exist:

ALTER TABLE `surveytable` ADD IF NOT EXISTS  Survey_Name_Qualtrics VARCHAR(20);
ALTER TABLE `surveytable` ADD IF NOT EXISTS Survey_URL_Qualtrics VARCHAR(600);

Answer 1

    CREATE PROCEDURE addcol() BEGIN
      IF NOT EXISTS(
        SELECT * FROM information_schema.COLUMNS
        WHERE COLUMN_NAME='new_column' AND TABLE_NAME='the_table' AND TABLE_SCHEMA='the_schema'
        )
    THEN
        ALTER TABLE `the_schema`.`the_table`
        ADD COLUMN `new_column` bigint(20) unsigned NOT NULL default 1;

       END IF;
    END;


     delimiter ';'

     CALL addcol();

DROP PROCEDURE addcol;

This is the code that i use, i dont think you can use if not exists on a ALTER column.

An alternative you can watch for the error you get if you try to insert a column that already exists, i think its 1062. And handle the error.

Of course the better way is to not get the error in the first place.