mysql判断列是否存在

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;