mysql判断表中字段或者索引是否存在,如果不存在则创建
判断字段是否存在:
DROP PROCEDURE IF EXISTS schema_change; DELIMITER // CREATE PROCEDURE schema_change() BEGIN DECLARE CurrentDatabase VARCHAR(100); 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();
判断索引是否存在:
DROP PROCEDURE IF EXISTS schema_change; DELIMITER // CREATE PROCEDURE schema_change() BEGIN DECLARE CurrentDatabase VARCHAR(100); 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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