mysql判断列是否存在

本篇文章将通过存储过程来判断列（字段）是否存在。请看详情。

推荐课程：MySQL教程。

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.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 0 COMMENT '是否上传 是否上传'; END IF;   END//   DELIMITER ;   CALL schema_change();

mysql 判断字段否存在，如果存在就修改字段：

DROP PROCEDURE IF EXISTS proc_tempPro; if(@count>0) THEN   alter table 表名 change column `旧列名` `新列名` varchar(30) comment '字段说明'; end if; end; call proc_tempPro; DROP PROCEDURE IF EXISTS proc_tempPro;

通过存储过程判断字段是否存在，不存在则增加：

DROP PROCEDURE IF EXISTS pro_AddColumn; CREATE PROCEDURE pro_AddColumn() BEGIN IF NOT EXISTS(SELECT 1 FROM information_schema.columns WHERE table_name='component' AND COLUMN_NAME='PRINT_CHECK_STATUS') THEN ALTER TABLE component ADD PRINT_CHECK_STATUS int(10) default 0; END IF; IF NOT EXISTS(SELECT 1 FROM information_schema.columns WHERE table_name='component' AND COLUMN_NAME='PRINT_CHECK_TIME') THEN ALTER TABLE component ADD PRINT_CHECK_TIME datetime NULL; END IF; IF NOT EXISTS(SELECT 1 FROM information_schema.columns WHERE table_schema=podcloud AND table_name='component' AND COLUMN_NAME='PRINT_CHECK_BACK_REASON') THEN ALTER TABLE component ADD PRINT_CHECK_BACK_REASON varchar(500) default null; END IF; END; CALL pro_AddColumn; DROP PROCEDURE pro_AddColumn;  ------------------------------------------------------------------------------------------------ DROP PROCEDURE IF EXISTS pro_AddIndex;    DELIMITER;  CREATE PROCEDURE pro_AddIndex() BEGIN 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 pro_AddIndex();  Drop procedure pro_AddIndex;

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