Question

我有一个带有DeptCode的员工表。我想要在Employee表中列出不同的DeptCode及其第一个创建日期。这还将告知哪个员工首次进入员工表中的特定部门。

我用过：

SELECT DISTINCT DEPTCODE, 
                CREATEDDATE 
FROM   EMPLOYEE

日期返回不正确。

处理此问题的任何特定语法。

Answer 1

尝试：

SELECT DEPTCODE, 
       Min(CREATEDDATE) 
FROM   EMPLOYEE 
GROUP  BY DEPTCODE

Answer 2

如果您需要部门代码，最早的创建日期，和员工的姓名，那么我会推荐窗口功能：

select deptcode, name, createddate
from (select e.*,
             row_number() over (partition by deptcode order by createddate) as seqnum
      from employee e
     ) e
where seqnum = 1;

Answer 3

您可以使用GROUP BY和MIN来实现此目标。

SELECT DEPTCODE, MIN(CREATEDDATE)
from EMPLOYEE
GROUP BY DEPTCODE

Answer 4

像这样。

SELECT deptcode, 
       employee_name, 
       minddate 
FROM   employee 
       JOIN (SELECT deptcode, 
                    Min(createddate) mindate 
             FROM   employee 
             GROUP  BY deptcode) temp 
         ON employee.deptcode = temp.deptcode 
            AND createddate = mindate

DISTINCT查询的SQL语法

4 个答案: