MySQL: How to add a column if it doesn't already exist?

alter-table, mysql

Solution

Use the following in a stored procedure:

IF NOT EXISTS( SELECT NULL
            FROM INFORMATION_SCHEMA.COLUMNS
           WHERE table_name = 'tablename'
             AND table_schema = 'db_name'
             AND column_name = 'columnname')  THEN

  ALTER TABLE `TableName` ADD `ColumnName` int(1) NOT NULL default '0';

END IF;

Reference:

- The INFORMATION_SCHEMA COLUMNS Table

Problem

I want to add a column to a table, but I don't want it to fail if it has already been added to the table. How can I achieve this? ``` # Add column fails if it already exists ALTER TABLE `TableName` ADD `ColumnName` int(1) NOT NULL default '0'; ```

Original source

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