SQL (MySQL)

查詢table更新時間

select UPDATE_TIME FROM information_schema.TABLES where TABLE_NAME='{}'

SHOW VARIABLES LIKE '%group_concat%';

SET GLOBAL group_concat_max_len=102400;

SET SESSION group_concat_max_len=102400;

ON DUPLICATE KEY UPDATE

ALTER TABLE Persons ADD UNIQUE (Id_P) 

GROUP_CONCAT()

update update_test A inner join (select PAY_DATE,sum(EXPENSE) as U1,max(EXPENSE) as U2 from expense where PAY_DATE >= '2020/4/1' group by PAY_DATE) B on A.PAY_DATE=B.PAY_DATE set A.SUM_PAY=B.U1,A.MAX_PAY=B.U2;

數字轉字串
CONVERT(1,CHAR)

修改表格名
ALTER TABLE `原表格名` RENAME TO `新表格名`

改欄位名稱
ALTER TABLE `表格名` CHANGE COLUMN `舊欄位名` `新欄位名` 欄位類型
ALTER TABLE mfg_skill CHANGE COLUMN STAGE DEPT varchar(6)