學習sql

SELECT ub.uid,ub.username, SUBSTRING(ub.time,1,10), SUBSTRING(MIN(ub.time),12,20) as 「簽到時間」, SUBSTRING(MAX(ub.time),12,20) as 「簽退時間」, (SELECT nub.time from userbuling nub WHERE nub.uid = ub.uid GROUP

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