SQL 語言 題目

2013-12-18 1:31 am
FLAT (FlatNo, Area, FlatSize, OwnerNo)
OWNER (OwnerNo, OwnerName, OwnerTel)

Show the owner number and the owner name of the owners who own more than one
flat.

回答 (4)

2013-12-19 4:06 am
select count(OwnerNo), OwnerNo, OwnerName from FLAT,OWNER where
FLAT.OwnerNo = OWNER.OwnerNO group by OwnerNo having count(OwnerNo)>1;
參考: me
2013-12-19 1:23 am
解說;
第一件事要做係找出所有owner有多個一個flat,句法係咁
select ownerNo from flats group by ownerNo having count(*)>1
注意係不可以用where,因為count並不是在table內的資料,而是全部record找出才知,所以要用having。
跟住,呢句好易,要找出OwnerNo,OwnerName,簡單之極
select OwnerNo,OwnerName from Owner
搞掂。不,仲爭一樣野,只要多過一個flat,所以後面加
where OwnerNo in (XXX)
而xxx則是剛才第一部份那句 select。
完整句子就係

select OwnerNo,OwnerName from Owner
where OwnerNo in (select ownerNo from flats group by ownerNo having count(*)>1
)
你答那句where flatNo>1錯到離譜,因為flatNo係房子的編號,不是數目。而且很可能是char,不可以>1。
2013-12-18 10:25 pm
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2013-12-18 2:14 am
留意Flat No係Flat個表度,
唔可以Select左Owner表之後直接換表,
要加子查詢先得。


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