c# - SQL重复记录查询

Question

我有两张 table 。

1. MasterStudent(学号、姓名、地址、出生日期)
2. 登机点(boardingID、student_number、区间数)

我想在生日之前获取重复的学生，但我不知道如何获取重复的记录。我是sql新手。我尝试了这个查询:

SELECT T.GivenName + ' ' + T.SurName AS Name,
  T.StreetNumber + ' ' + T.StreetName + ' ' + T.Suburb + ' ' + T.PostCode + ' ' + T.State + ' ' + T.Country AS Address,
  T.Sex, 
  T.DateOfBirth,
  T.yearlevel AS Year,
  z.dupCount,
  T.StudentNumber
FROM tblMasterStudent AS T
INNER JOIN (SELECT DateOfBirth, COUNT(*) AS dupCount
            FROM tblMasterStudent
            GROUP BY DateOfBirth
            HAVING (COUNT(*) > 1)) AS z ON z.DateOfBirth = T.DateOfBirth
            ORDER BY z.dupCount DESC

它正在从 MasterStudent 表中按生日获取重复记录，但我想从 masterStudent+BoardingPoint 获取记录

Answer 1

您可以按生日分组并查看所有多次出现的生日:

SELECT count(1) as frequency, dob
FROM students
GROUP BY dob
HAVING frequency > 1;