Question

有人可以告诉我如何将这些查询嵌套到一个完整的查询中吗？现在，我一次只运行一个（最多10个），但我想学习如何一次性运行这个查询。

Dim queryString1 As String = 
"SELECT EMPLOYEE_NAME, AVG(EFFICIENCY_YIELD) AS YIELD 
 FROM dbo.APE_BUSDRIVER_MAIN 
 WHERE APE_AREA_OBJID = " & lblAreaOBJID.Text & " 
 AND ACTIVE = 1 
 GROUP BY EMPLOYEE_NAME ORDER BY YIELD " & lblSortOrder.Text & ""


Dim queryString2 As String = 
"SELECT EMPLOYEE_NAME, AVG(EFFICIENCY_YIELD) AS YIELD 
 FROM dbo.APE_BUSDRIVER_MAIN 
 WHERE APE_AREA_OBJID = " & lblAreaOBJID.Text & " 
 AND ACTIVE = 1  
 AND EMPLOYEE_NAME <> '" & LblStckRnk1.Text & "' 
 GROUP BY EMPLOYEE_NAME 
 ORDER BY YIELD " & lblSortOrder.Text & ""


Dim queryString3 As String = 
"SELECT EMPLOYEE_NAME, AVG(EFFICIENCY_YIELD) AS YIELD 
 FROM dbo.APE_BUSDRIVER_MAIN 
 WHERE APE_AREA_OBJID = " & lblAreaOBJID.Text & " 
 AND ACTIVE = 1  
 AND EMPLOYEE_NAME <> '" & LblStckRnk1.Text & "' 
 AND EMPLOYEE_NAME <> '" & LblStckRnk2.Text & "' 
 GROUP BY EMPLOYEE_NAME 
 ORDER BY YIELD " & lblSortOrder.Text & ""

Answer 1

我会使用一些UNION语句：

Dim queryString1 As String = "SELECT EMPLOYEE_NAME, AVG(EFFICIENCY_YIELD) AS YIELD
  FROM dbo.APE_BUSDRIVER_MAIN WHERE APE_AREA_OBJID = " & lblAreaOBJID.Text & " AND ACTIVE = 1 
  GROUP BY EMPLOYEE_NAME ORDER BY YIELD " & lblSortOrder.Text & vbCrLf & _

" UNION " & vbCrLf & _

"SELECT EMPLOYEE_NAME, AVG(EFFICIENCY_YIELD) AS YIELD 
  FROM dbo.APE_BUSDRIVER_MAIN 
  WHERE APE_AREA_OBJID = " & lblAreaOBJID.Text & " AND ACTIVE = 1 
  AND EMPLOYEE_NAME <> '" & LblStckRnk1.Text & "' 
  GROUP BY EMPLOYEE_NAME ORDER BY YIELD " & lblSortOrder.Text & vbCrLf & _

" UNION " & vbCrLf & _

"SELECT EMPLOYEE_NAME, AVG(EFFICIENCY_YIELD) AS YIELD 
  FROM dbo.APE_BUSDRIVER_MAIN 
  WHERE APE_AREA_OBJID = " & lblAreaOBJID.Text & " AND ACTIVE = 1 
  AND EMPLOYEE_NAME <> '" & LblStckRnk1.Text & "' AND EMPLOYEE_NAME <> '" & LblStckRnk2.Text & "' 
  GROUP BY EMPLOYEE_NAME ORDER BY YIELD " & lblSortOrder.Text

（当然，您需要删除我为了便于阅读而添加的额外换行符）

Answer 2

让我们检查这些查询返回的内容：

（所有三个使用相同的组和相同的顺序）

1-返回“areaFooBar”

中的所有“活跃”员工

2-返回“areaFooBar”的所有“活跃”员工减去一名员工

3-返回“areaFooBar”的所有“活跃”员工减去两名员工

您可以在代码中执行此类过滤。您不必运行查询2或查询3。重新迭代查询1的结果集并过滤您不想包含的员工。

每次都必须从数据库中读取它，如果你这么做就可以使用一个queryString 在查询中再添加一个参数，即：逗号分隔列表。文本

Dim queryString1 As String = 
"
 SELECT EMPLOYEE_NAME, AVG(EFFICIENCY_YIELD) AS YIELD 
 FROM dbo.APE_BUSDRIVER_MAIN 
 WHERE APE_AREA_OBJID = " & lblAreaOBJID.Text & " 
 AND ACTIVE = 1 
 EMPLOYEE_NAME NOT IN ( " & comma-separated-list.Text & " ) 
 GROUP BY EMPLOYEE_NAME ORDER BY YIELD " & lblSortOrder.Text & ""

如何嵌套多个SQL查询？

2 个答案: