我如何（或可以）在多列上选择 DISTINCT？

SELECt DISTINCT a,b,c FROM t

是大致等效于：

SELECt a,b,c FROM t GROUP BY a,b,c

习惯 GROUP BY 语法是个好主意，因为它更强大。

对于您的查询，我会这样做：

UPDATe salesSET status='ACTIVE'WHERe id IN(    SELECT id    FROM sales S    INNER JOIN    (        SELECt saleprice, saledate        FROM sales        GROUP BY saleprice, saledate        HAVINg COUNT(*) = 1     ) T    ON S.saleprice=T.saleprice AND s.saledate=T.saledate )