如何在WHERE子句中使用Distinct

Question

我有这个查询来统计员工在一个月内的礼物数。

SELECT DISTINCT 
    COUNT([Attendance].[Status])
FROM
    [HRM].[tbl_EmployeeAttendance] [Attendance], [HRM].[tbl_EmployeeInfo] [Info]
WHERE 
    [Attendance].[Status] IN ('Early Left', 'Present', 'Half Day', 'Late In')
    AND [Info].[ID] = [Attendance].[EmpCode] 
    AND [Attendance].[EmpCode] = 266 
    AND CAST([Attendance].[AttendanceTimeIn] AS DATE) >= '2018-08-01' 
    AND CAST([Attendance].[AttendanceTimeOut] AS DATE) <= '2018-08-15'

现在有很多员工被标记为两次或三次出勤。 就像一旦雇员离职，他的出勤就被安排成一次外出，而一旦他来就比按时来待。 因此，现在可以算是增加了同一天的出勤次数。 我想获得日期之间的不同日期。

这是示例数据：

2018-04-04 18:12:30  2018-04-04 19:38:12   266  Present
2018-04-04 09:43:01  2018-04-04 09:58:41   266  Present
2018-04-05 16:40:52  2018-04-05 18:40:52   266  Present
2018-04-06 11:35:59  2018-04-06 11:48:49   266  Present

现在它是两次对日期4进行计数，但是应该对它进行一次计数。

Answer 1

DISTINCT应该在COUNT()内部

因此，它将是：

SELECT COUNT(DISTINCT [Attendance].[Status]), 
       COUNT(DISTINCT CAST([Attendance].[AttendanceTimeIn] AS Date))
. . .

但是，我建议在FROM子句中使用适当的标准，显式JOIN语法代替逗号：

SELECT COUNT(DISTINCT [Attendance].[Status]),
       COUNT(DISTINCT CAST([Attendance].[AttendanceTimeIn] AS Date))
FROM [HRM].[tbl_EmployeeAttendance] [Attendance] INNER JOIN
     [HRM].[tbl_EmployeeInfo] [Info]
     ON [Info].[ID] = [Attendance].[EmpCode] 
WHERE [Attendance].[Status] IN ('Early Left', 'Present', 'Half Day', 'Late In') AND 
      [Attendance].[EmpCode] = 266 AND 
      CAST([Attendance].[AttendanceTimeIn] AS DATE) >= '2018-08-01'AND 
      CAST([Attendance].[AttendanceTimeOut] AS DATE) <= '2018-08-15'

Answer 2

尝试此操作以显示最新日期并执行独特的

SELECT COUNT(DISTINCT CAST([Attendance].[AttendanceTimeIn] as Date))
FROM [HRM].[tbl_EmployeeAttendance] [Attendance], [HRM].[tbl_EmployeeInfo] [Info]
WHERE [Attendance].[Status] IN ('Early Left', 'Present', 'Half Day', 'Late In')
AND [Info].[ID] = [Attendance].[EmpCode] AND [Attendance].[EmpCode] = 266 
AND CAST([Attendance].[AttendanceTimeIn] AS DATE) >= '2018-08-01' 
AND CAST([Attendance].[AttendanceTimeOut] AS DATE) <= '2018-08-15'