Augusto Souza augusto-gtns
jeremyjarrell
/ Idempotent migration in MySQL example
Created
July 25, 2013 20:06
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.
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| 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 |