Alter Table if Column Not Exist in MySQL
To alter the table if the column does not exist:
IF NOT EXISTS( SELECT NULL
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_name = 'tableName'
AND table_schema = 'database_name'
AND column_name = 'columnName') THEN
ALTER TABLE `TableName` ADD `ColumnName` int(1) NOT NULL default '0';
END IF;