Question

我正在运行SQL Server，我正在尝试从CRM应用程序加入多个表，但我无法得到我需要的结果。我发现这篇文章SQL Server: Multiple table joins with a WHERE clause包含了我正在寻找的信息，但我无法让它工作。

我有5张桌子

机器表

- MachID       Name
-   1         Mach1
-   2         Mach2
-   3         Mach3

维护表

- MaintID       StatusCode
-   1                1
-   2                1

维护扩展表

- MaintID      MaintName              StartDate               EndDate              MachId
-   1         Maint Test 1    2015-02-01 05:00:00.000    2015-02-03 05:00:00.000     2
-   2         Maint Test 2    2015-02-06 05:00:00.000    2015-02-09 05:00:00.000     2

日程表

- SchedID       StatusCode
-   1                1
-   2                1

安排扩展表

- SchedID      SchedName              StartDate               EndDate               MachId     JobNumber
-   1         Sched Test 1    2015-01-15 05:00:00.000    2015-01-19 05:00:00.000       2        1111
-   2         Sched Test 2    2015-01-20 05:00:00.000    2015-01-23 05:00:00.000       2        2222

所以我尝试这个查询，因为我想得到一组数据，当Maint事件中有一个NULL时，它会显示一个Schedule事件的行项目，同样在有一个时显示Maint事件并且为NULL在附表活动中。如果只有两个，那么只显示那个没有任何内容的项目。

DECLARE @StartDate DATETIME
DECLARE @EndDate DATETIME
SET @StartDate = '1/05/15'
SET @EndDate = '5/2/15'
SELECT
     mn.name AS MachineName
    ,se.Schedname AS SchedName
    ,me.Maintname AS MaintName
    ,se.StartDate AS SchStartDate
    ,se.EndDate AS SchEndDate
    ,se.JobNumber
    ,sb.statuscode AS SchStat
    ,mb.statuscode AS MaintStat
    ,me.StartDate AS MaintStartDate
    ,me.EndDate AS MaintEndDate
FROM [machines] AS mn
INNER JOIN [MaintenanceExtension] AS me
ON mn.MachId = me.MachId
INNER JOIN [Maintenance] AS mb
ON me.MaintId = mb.MaintId
INNER JOIN [ScheduleExtension] as se
ON se.MachId = mn.MachId
INNER JOIN [Schedule] AS sb
ON sb.SchedId = se.SchedId
WHERE  se.StartDate between @StartDate and @EndDate

我得到的，似乎包括带有Schedule项的MaintStartDate，反之亦然。为什么对立列不显示NULL？

MachineName    SchedName    MaintName             SchStartDate             SchEndDate           JobNumber     SchStat     MaintStat       MaintStartDate            MaintEndDate
   Mach2      SCH TEST 1    MAINT TEST 1       2015-01-15 05:00:00.000  2015-01-19 05:00:00.000   12345         1            1        2015-02-01 05:00:00.000   2015-02-03 05:00:00.000
   Mach2      SCH TEST 2    MAINT TEST 1       2015-01-20 05:00:00.000  2015-01-23 05:00:00.000   7894          1            1        2015-02-01 05:00:00.000   2015-02-03 05:00:00.000
   Mach2      SCH TEST 1    MAINT TEST 2       2015-01-15 05:00:00.000  2015-01-19 05:00:00.000   12345         1            1        2015-02-06 05:00:00.000   2015-02-09 05:00:00.000
   Mach2      SCH TEST 2    MAINT TEST 2       2015-01-20 05:00:00.000  2015-01-23 05:00:00.000   7894          1            1        2015-02-06 05:00:00.000   2015-02-09 05:00:00.000

我正在寻找的是这样的：

MachineName    SchedName    MaintName             SchStartDate             SchEndDate           JobNumber     SchStat     MaintStat       MaintStartDate            MaintEndDate
   Mach2      SCH TEST 1      NULL          2015-01-15 05:00:00.000 2015-01-19 05:00:00.000       1111          1            1                NULL                    NULL
   Mach2      SCH TEST 2      NULL          2015-01-20 05:00:00.000 2015-01-23 05:00:00.000       2222          1            1                NULL                    NULL
   Mach2         NULL    MAINT TEST 1               NULL                      NULL                NULL          1            1        2015-02-01 05:00:00.000   2015-02-03 05:00:00.000
   Mach2         NULL    MAINT TEST 2               NULL                      NULL                NULL          1            1        2015-02-06 05:00:00.000   2015-02-09 05:00:00.000

Answer 1

INNER JOIN表示您想要连接两个表，其中列填充在两个表中。由于您需要具有MaintenanceExtension或ScheduleExtension的计算机的所有结果，因此请尝试使用此尺寸。

DECLARE @StartDate DATETIME
DECLARE @EndDate DATETIME
SET @StartDate = '1/05/15'
SET @EndDate = '5/2/15'
SELECT
     mn.name AS MachineName
    ,se.Schedname AS SchedName
    ,me.Maintname AS MaintName
    ,se.StartDate AS SchStartDate
    ,se.EndDate AS SchEndDate
    ,se.JobNumber
    ,sb.statuscode AS SchStat
    ,mb.statuscode AS MaintStat
    ,me.StartDate AS MaintStartDate
    ,me.EndDate AS MaintEndDate
FROM [machines] AS mn
LEFT JOIN [MaintenanceExtension] AS me
ON mn.MachId = me.MachId
LEFT JOIN [Maintenance] AS mb
ON me.MaintId = mb.MaintId
LEFT JOIN [ScheduleExtension] as se
ON se.MachId = mn.MachId
LEFT JOIN [Schedule] AS sb
ON sb.SchedId = se.SchedId
WHERE  se.StartDate between @StartDate and @EndDate

这将为您提供所有结果，包括既没有MaintenanceExtension也没有ScheduleExtension的计算机。如果要限制具有一个或另一个的计算机，则需要使用where where子句。

WHERE  se.StartDate between @StartDate and @EndDate
  AND  (me.MachId IS NOT NULL OR se.MachID IS NOT NULL)

最后，如果要排除同时具有这两者的计算机，则需要使用where where子句。

WHERE  se.StartDate between @StartDate and @EndDate
  AND  (me.MachId IS NOT NULL OR se.MachID IS NOT NULL)
  AND  (me.MachId IS NULL OR se.MACHId IS NULL)

SQL Server：具有一个或多个WHERE子句的多个表连接

1 个答案: