判断字段是否存在:
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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_order
ADD COLUMN `IfUpSend` BIT NOT NULL DEFAULT COMMENT '是否上传 是否上传' ;
END IF;
END //
DELIMITER ;
CALL schema_change();
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判断索引是否存在:
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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();
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从这两段可以看出很多东西,具体可以自己试验一下
关于小编给大家介绍的Mysql判断表字段或索引是否存在的内容就给大家介绍到这里,希望对大家有所帮助!