jeremyjarrell
/ Idempotent migration in MySQL example
Created Jul 25, 2013
In MySQL, IF statements cannot exist outside of stored procedures. Therefore, to create an idempotent migration for MySQL it's necessary to wrap the migration in a stored procedure and execute that stored procedure against the database to perform the migration.
View Idempotent migration in MySQL example
| DELIMITER $$ | |
| DROP PROCEDURE IF EXISTS add_email_address_column_to_customers_table $$ | |
| -- Create the stored procedure to perform the migration | |
| CREATE PROCEDURE add_email_address_column_to_customers_table() | |
| BEGIN | |
| -- Add the email_address column to the customers table, if it doesn't already exist |