mysql日期函數及重複數據的查詢

-- 日期函數
select CURRENT_DATE,CURRENT_TIME,CURRENT_TIMESTAMP,year(CURRENT_DATE),month(CURRENT_DATE);
select * from sr_main where TIMESTAMPDIFF(DAY,SYS_CREATETIME,SYSDATE())>7 and SYS_SPZT <>1 ;

1.目標查出表中重複的身份證
-- 如下爲錯誤寫法由於 where 後面不能用聚合函數
select * from sr_main where mhzsfz in (
select mhzsfz from sr_main where count(MHZSFZ)>1
)
-- 正確寫法
select * from sr_main where mhzsfz in (
select mhzsfz from sr_main GROUP BY mhzsfz having count(mhzsfz)>1
)

1.目標查出表中重複的身份證且數據爲2019年，單據類型爲db_jz，時間爲2019年
select * from sr_main a where mhzsfz in (
select mhzsfz from sr_main GROUP BY mhzsfz having count(mhzsfz)>1
) and SYS_CREATETIME like concat('2019','%') and INSTR('db_jz',a.mdjlx)>1;