Question

我有一张叫做登记的桌子。学生A有3条记录，其中两条记录具有相同的start_date。

我想在postgres中找到所有具有相同2013年开学日期的学生。

报名：

StudentID   Start_Date      Syear school_id
1             2013-06-21    2013    10
1             2013-06-21    2013    11 
1             2014-02-21    2014    10

提前致谢。

Answer 1

SELECT StudentID, Start_Date
FROM
(
    SELECT StudentID, Start_date, COUNT(*) OVER (PARTITION BY start_date) count
    FROM Student
)
WHERE count > 1

或

SELECT StudentID, Start_Date
FROM Student S1
WHERE EXISTS (
    SELECT *
    FROM Student S2
    WHERE S1.Start_Date = S2.Start_Date AND S1.StudentID <> S2.StudentID
)

如何比较postgres中的两个字段？

1 个答案: