Question

我有两个查询，我想在SQL中加入第二个查询和第二个查询，这是我的查询，

第一次查询

OleDbCommand Query1 = new OleDbCommand();
Query.CommandText = "SELECT [Mastertable].ID " +
"FROM [Mastertable] INNER JOIN [relationship] ON [Mastertable].ID = [relationship].SW1_ID " +
"WHERE ([Mastertable].[PN]= @PN AND [Mastertable].[Ver]=@Ver) " +
"GROUP BY [Mastertable].[ID]";

DataSet ResultSet = RunQuery(Query1);

以上查询基本返回ID为PN = PN输入和Ver =版本输入。（我把结果放在数据集中

我想从query1加入ID列到Mastertable。 ID再次

第二个查询，

OleDbCommand Query2 = new OleDbCommand();
Query2.CommandText = "SELECT [Mastertable].PN, [Mastertable].[Ver], [relationship].[Category], [Mastertable].[Component_Name] " +
"FROM (Query1 INNER JOIN [relationship] ON Query1.[ID] = [relationship].SID) INNER JOIN " +
"[Mastertable] ON [relationship].SW2_ID = [Mastertable].[ID]";

DataSet ResultSet2 = RunQuery(Query2);

但是这段代码不起作用，我在网上搜索了很多并尝试了一些，但他们没有帮助。我正在考虑使用ResultSet1.Tables [0] .TableName和ResultSet1.Tables [0] .Columns [0] .Name，但这不起作用=（

请帮忙

Answer 1

您可以将Query1作为派生表连接到第二个（外部）Query2，如下所示：

SELECT [SW Mastertable].SW_PN, [SW Mastertable].[SW_Ver], 
       [SW relationship].[SW2_Category], [SW Mastertable].[Component_Name]
FROM 
  (SELECT [Mastertable].ID
    FROM [Mastertable] 
      INNER JOIN [relationship] ON [Mastertable].ID = [relationship].SW1_ID
    WHERE ([Mastertable].[PN]= @PN AND [Mastertable].[Ver]=@Ver)
    GROUP BY [Mastertable].[ID]
  ) Query1
  INNER JOIN [SW relationship] ON Query1.[ID] = [SW relationship].SW1_ID) 
  INNER JOIN [SW Mastertable] ON [SW relationship].SW2_ID = [SW Mastertable].[ID];

如果您使用的是sql-server，您也可以使用CTE执行此操作：

WITH Query1 AS
(
  SELECT [Mastertable].ID
    FROM [Mastertable] 
        INNER JOIN [relationship] ON [Mastertable].ID = [relationship].SW1_ID
    WHERE ([Mastertable].[PN]= @PN AND [Mastertable].[Ver]=@Ver)
    GROUP BY [Mastertable].[ID]
)
SELECT [SW Mastertable].SW_PN, [SW Mastertable].[SW_Ver], 
       [SW relationship].[SW2_Category], [SW Mastertable].[Component_Name]
FROM 
  Query1
    INNER JOIN [SW relationship] ON Query1.[ID] = [SW relationship].SW1_ID) 
    INNER JOIN [SW Mastertable] ON [SW relationship].SW2_ID = [SW Mastertable].[ID];

Answer 2

不确定这是否有效，但你仍然可以尝试一下。如果有的话，请修复语法错误。

此外，我假设您在尝试创建Query2对象时可以使用Query1对象（即不为null或不在范围之外）。

OleDbCommand Query2 = new OleDbCommand();
Query2.CommandText = "SELECT [SW Mastertable].SW_PN, [SW Mastertable].[SW_Ver], [SW relationship].[SW2_Category], [SW Mastertable].[Component_Name], [SW relationship].SW2_ID " +
"FROM (("+ Query1.CommandText +")TAB1 INNER JOIN [SW relationship] ON TAB1.[ID] = [SW relationship].SW1_ID) TAB2 INNER JOIN " +
"[SW Mastertable] ON [TAB2].SW2_ID = [SW Mastertable].[ID]";

DataSet ResultSet2 = RunQuery(Query2);

希望这有帮助。

Answer 3

OleDbCommand Query2 = new OleDbCommand();
Query2.CommandText = "SELECT [SW Mastertable].SW_PN, [SW Mastertable].[SW_Ver], [SW relationship].[SW2_Category]," + 
" [SW Mastertable].[Component_Name] " +
" FROM " +
"(SELECT [Mastertable].ID as ID " +
"FROM [Mastertable] INNER JOIN [relationship] ON [Mastertable].ID = [relationship].SW1_ID " +
"WHERE ([Mastertable].[PN]= @PN AND [Mastertable].[Ver]=@Ver) " +
"GROUP BY [Mastertable].[ID]) as Query1 " +
" INNER JOIN [SW relationship] ON Query1.[ID] = [SW relationship].SW1_ID INNER JOIN " +
"[SW Mastertable] ON [SW relationship].SW2_ID = [SW Mastertable].[ID]";

DataSet ResultSet2 = RunQuery(Query2);

如何将查询加入另一个查询

3 个答案: