Question

我有两张表。University和UniversityType。结构看起来像这样。对于大学

    universityId universityName universityTypeId universityTypeName
        1            xyz              1                UGC
        2            abc              1                UGC
        3            lmn              2                NCT
        4            pqr              3                AICT

UniversityType

    universityTypeId  universityTypeName
          1                UGC
          2                NCT
          3                AICT

UniversityType表是固定的。现在我想获得大学类型的计数，即UGC = 2，AICT = 1，NCT = 1.现在我写的是这样的

    SELECT universityId,universityTypeId,universityName FROM 
    University where universityTypeId=:universityTypeId";

但我没有得到正确的结果。任何人都可以告诉我。我是SQL新手。

Answer 1

SELECT universityTypeId, COUNT(1) 
FROM University where universityTypeId=:universityTypeId

OR

SELECT universityTypeId, COUNT(1) 
FROM University
GROUP BY universityTypeId

OR

SELECT universityTypeId, (SELECT COUNT(1) 
    FROM University where universityTypeId = UniversityType.universityTypeId)
     FROM UniversityType

Answer 2

喜欢这个

SELECT universityId,universityName,count(universityTypeId) as total  FROM 
University group by universityId,universityName

除非在聚合函数

中使用，否则必须在group by子句中添加所有列列表

Answer 3

select universityTypeName, COUNT(University.universityId) FROM UniversityType JOIN University  ON UniversityType.universityTypeId = University.universityTypeId GROUP BY UniversityType.universityTypeName

尝试此查询

Answer 4

您需要按UniversityType.universityTypeId加入表格并计算University。所以，试试这个：

SELECT t.universityTypeName, count(u.universityId) as total 
FROM University u, UniversityType t 
WHERE u.universityTypeId = t.universityTypeId 
GROUP BY u.universityTypeName;

它给出的输出是：

UGC|2
NCT|1
AICT|1

涉及多个表的SQL计数

4 个答案: