Question

我有100人的桌子EMPLOYEE。我想写一个查询来查找具有相同BIRTHDATE的员工对。

结果应该为对中的每个雇员返回EMPNO，LASTNAME和BIRTHDATE（6列结果表）。

我认为这样的事情

SELECT  t1.EmpNo
       ,t1.LastName
       ,t1.BirthDate
        ,t2.EmpNo
        ,t2.LastName
        ,t2.BirthDate
  FROM Employee t1
  INNER JOIN (
  SELECT EmpNo
        ,LastName
        ,BirthDate
  FROM Employee ) t2 ON t2.BirthDate = t1.BirthDate 
  WHERE t2.EmpNo != t1.EmpNo

你认为这是对的吗？

Answer 1

我会这样做：

SELECT t1.EmpNo, 
       t1.LastName, 
       t1.BirthDate, 
       t2.EmpNo, 
       t2.LastName, 
       t2.Birthdate
FROM Employee t1, Employee t2
WHERE t1.BirthDate = t2.Birthdate
AND t1.EmpNo <> t2.EmpNo

Answer 2

看起来不错但我会删除第二个选择.. 子查询

SELECT 
t1.EmpNo ,t1.LastName ,t1.BirthDate ,t2.EmpNo ,t2.LastName ,t2.BirthDate 
FROM Employee t1 
INNER JOIN Employee t2 ON t2.BirthDate = t1.BirthDate 
WHERE t2.EmpNo != t1.EmpNo

Answer 3

我还会添加t1.EmpNo<t1.EmpNO以避免重复的条件。

Answer 4

这是我的回答

Select name, date From employees Group by date of birth Having count(*)>1;

查询以查找具有相同生日的员工对

4 个答案: