判斷字段是否存在：
| DROP PROCEDURE IF EXISTS schema_change; DELIMITER //CREATE PROCEDURE schema_change() BEGIN DECLARE CurrentDatabase VARCHAR();SELECT DATABASE() INTO CurrentDatabase;IF NOT EXISTS (SELECT * FROM information_schema.columns WHERE table_schema=CurrentDatabase AND table_name = 'rtc_order' AND column_name = 'IfUpSend') THEN ALTER TABLE rtc_orderADD COLUMN `IfUpSend` BIT NOT NULL DEFAULT COMMENT '是否上傳 是否上傳';END IF; END// DELIMITER ; CALL schema_change(); |
判斷索引是否存在：
| DROP PROCEDURE IF EXISTS schema_change; DELIMITER //CREATE PROCEDURE schema_change() BEGIN DECLARE CurrentDatabase VARCHAR();SELECT DATABASE() INTO CurrentDatabase;IF NOT EXISTS (SELECT * FROM information_schema.statistics WHERE table_schema=CurrentDatabase AND table_name = 'rtc_phototype' AND index_name = 'index_name') THEN ALTER TABLE `rtc_Phototype` ADD INDEX index_name ( `imgtype` );END IF; END// DELIMITER ; CALL schema_change(); |
從這兩段可以看出很多東西，具體可以自己試驗一下
關于小編給大家介紹的Mysql判斷表字段或索引是否存在的內容就給大家介紹到這里，希望對大家有所幫助！
新聞熱點
疑難解答
