mysql在增加列前进行判断该列是否存在

Posted 2021-01-19 ︶ㄣ霞光里

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;

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_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;　
 

插入语句判断是否存在，不存在则插入：

insert into permission(id,name,navigation_id,parentid) select ‘130‘,‘印前审查‘,null,‘1‘ from DUAL WHERE NOT EXISTS(SELECT * FROM permission WHERE id=‘130‘);
insert into navigation(id,name,parent,path,seq_num,sub_sys,url) select ‘39‘,‘参数配置‘,11,‘/3/11‘,1,3,null from DUAL WHERE NOT EXISTS(SELECT * FROM navigation WHERE id=‘39‘);