MySQL添加列（如果不存在）

您可以为查询创建一个过程，

DELIMITER $$CREATE PROCEDURE Alter_Table()BEGIN    DECLARE _count INT;    SET _count = (  SELECt COUNT(*)          FROM INFORMATION_SCHEMA.COLUMNS         WHERe   TABLE_NAME = 'email_subscription' AND       COLUMN_NAME = 'subscribe_all');    IF _count = 0 THEN        ALTER TABLE email_subscription ADD COLUMN subscribe_all TINYINT(1) DEFAULT 1, ADD COLUMN subscribe_category varchar(512) DEFAULT NULL;    END IF;END $$DELIMITER ;