SELECT BorrowerMemNo AS BMN
FROM Book
WHERE 6=(SELECT COUNT(*)
FROM Book
WHERE BorrowerMemNo=BMN);
这样会出来6条相同的纪录但是如果加个distinct
SELECT DISTINCT BorrowerMemNo AS BMN
FROM Book
WHERE 6=(SELECT COUNT(*)
FROM Book
WHERE BorrowerMemNo=BMN);
返回为空,一条纪录都没
求问阿,困扰好几天了
FROM Book
WHERE 6=(SELECT COUNT(*)
FROM Book
WHERE BorrowerMemNo=BMN);
这样会出来6条相同的纪录但是如果加个distinct
SELECT DISTINCT BorrowerMemNo AS BMN
FROM Book
WHERE 6=(SELECT COUNT(*)
FROM Book
WHERE BorrowerMemNo=BMN);
返回为空,一条纪录都没
求问阿,困扰好几天了
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FROM Book这个的时候已经不是6条记录了。后面再等于6,那当然是不对了。
SELECT DISTINCT BorrowerMemNo AS BMN
FROM Book
WHERE 0=(SELECT COUNT(*)
FROM Book
WHERE BorrowerMemNo=BMN);
怎么一加distinct差别这么大
SELECT BorrowerMemNo AS BMN
FROM Book
WHERE 6=(SELECT COUNT(*)
FROM Book
WHERE BorrowerMemNo=BMN) GROUP BY BorrowerMemNo
这样再试一下.