LINQ的ORM功能中对使用sp_executesql语句的存储过程的支持

在实际的项目中，我们经常会碰到存储过程中需要使用sp_executesql语句的情形，如下：

1 IF EXISTS (SELECT * FROM sysobjects WHERE type = 'P' AND name = 'GetEmployeesByFilter')
2 BEGIN
3 DROP Procedure [GetEmployeesByFilter]
4 END
5
6 GO
7
8 CREATE Procedure [GetEmployeesByFilter]
9 (
10 @EmployeeNo NVarChar(50) = NULL,
11 @EmployeeName NVarChar(50) = NULL,
12 @DepartmentId Int = NULL,
13 @PositionId Int = NULL,
14 @EmployeeManager Int = NULL,
15 @BeginEmployeeEntryDate DateTime = NULL,
16 @EndEmployeeEntryDate DateTime = NULL,
17 @EmployeeStatus Int = NULL,
18 @PageSize Int = NULL,
19 @PageIndex Int = NULL,
20 @RecordCount Int = NULL OUTPUT
21 )
22
23 AS
24
25 BEGIN
26 DECLARE @MinIndex Int
27 DECLARE @MaxIndex Int
28 SET @MinIndex = (@PageIndex - 1) * @PageSize + 1
29 SET @MaxIndex = @MinIndex + @PageSize - 1
30
31 DECLARE @Where NVarChar(MAX)
32 SET @Where = '0 = 0'
33 IF @EmployeeNo IS NOT NULL
34 SET @Where = @Where + ' AND [EmployeeNo] LIKE ''%' + @EmployeeNo + '%'''
35 IF @EmployeeName IS NOT NULL
36 SET @Where = @Where + ' AND [EmployeeName] LIKE ''%' + @EmployeeName + '%'''
37 IF @DepartmentId IS NOT NULL
38 SET @Where = @Where + ' AND [DepartmentId] = ''' + CONVERT(NVarChar, @DepartmentId) + ''''
39 IF @PositionId IS NOT NULL
40 SET @Where = @Where + ' AND [PositionId] = ''' + CONVERT(NVarChar, @PositionId) + ''''
41 IF @EmployeeManager IS NOT NULL
42 SET @Where = @Where + ' AND [EmployeeManager] = ''' + CONVERT(NVarChar, @EmployeeManager) + ''''
43 IF @BeginEmployeeEntryDate IS NOT NULL
44 SET @Where = @Where + ' AND [EmployeeEntryDate] >= ''' + CONVERT(NVarChar, @BeginEmployeeEntryDate, 101) + ' ' + '00:00:00' + ''''
45 IF @EndEmployeeEntryDate IS NOT NULL
46 SET @Where = @Where + ' AND [EmployeeEntryDate] <= ''' + CONVERT(NVarChar, @EndEmployeeEntryDate, 101) + ' ' + '23:59:59' + ''''
47 IF @EmployeeStatus IS NOT NULL
48 SET @Where = @Where + ' AND [EmployeeStatus] = ''' + CONVERT(NVarChar, @EmployeeStatus) + ''''
49
50 DECLARE @Record NVarChar(MAX)
51 SET @Record = 'SELECT ROW_NUMBER() OVER(ORDER BY [EmployeeId]) AS [Index],
52 [EmployeeId],
53 [EmployeeNo],
54 [EmployeeName],
55 [DepartmentId],
56 [PositionId],
57 [EmployeeManager],
58 [EmployeeGender],
59 [EmployeeEntryDate],
60 [EmoplyeeBirthday],
61 [EmployeePhone],
62 [EmployeeEmail],
63 [EmployeeStatus]
64 FROM [Employee]
65 WHERE' + ' ' + @Where
66
67 DECLARE @Sql NVarChar(MAX)
68 SET @Sql = 'SELECT @RecordCount = COUNT(*)
69 FROM (' + @Record + ') DERIVEDTBL
70
71 SELECT [EmployeeId],
72 [EmployeeNo],
73 [EmployeeName],
74 [DepartmentId],
75 [PositionId],
76 [EmployeeManager],
77 [EmployeeGender],
78 [EmployeeEntryDate],
79 [EmoplyeeBirthday],
80 [EmployeePhone],
81 [EmployeeEmail],
82 [EmployeeStatus]
83 FROM (' + @Record + ') DERIVEDTBL
84 WHERE [Index] >= @MinIndex AND [Index] <= @MaxIndex'
85
86 DECLARE @Parameter NVarChar(MAX)
87 SET @Parameter = '@MinIndex Int, @MaxIndex Int, @RecordCount Int OUTPUT'
88
89 EXEC sp_executesql @Sql, @Parameter, @MinIndex, @MaxIndex, @RecordCount OUTPUT
90 END
91
92 GO

　　但在这种情况下，LINQ往往不能正确识别：

1 <Function Name="dbo.GetEmployeesByFilter" Method="GetEmployeesByFilter">
2 <Parameter Name="EmployeeNo" Parameter="employeeNo" Type="System.String" DbType="NVarChar(50)" />
3 <Parameter Name="EmployeeName" Parameter="employeeName" Type="System.String" DbType="NVarChar(50)" />
4 <Parameter Name="DepartmentId" Parameter="departmentId" Type="System.Int32" DbType="Int" />
5 <Parameter Name="PositionId" Parameter="positionId" Type="System.Int32" DbType="Int" />
6 <Parameter Name="EmployeeManager" Parameter="employeeManager" Type="System.Int32" DbType="Int" />
7 <Parameter Name="BeginEmployeeEntryDate" Parameter="beginEmployeeEntryDate" Type="System.DateTime" DbType="DateTime" />
8 <Parameter Name="EndEmployeeEntryDate" Parameter="endEmployeeEntryDate" Type="System.DateTime" DbType="DateTime" />
9 <Parameter Name="EmployeeStatus" Parameter="employeeStatus" Type="System.Int32" DbType="Int" />
10 <Parameter Name="PageSize" Parameter="pageSize" Type="System.Int32" DbType="Int" />
11 <Parameter Name="PageIndex" Parameter="pageIndex" Type="System.Int32" DbType="Int" />
12 <Parameter Name="RecordCount" Parameter="recordCount" Type="System.Int32" DbType="Int" Direction="InOut" />
13 <Return Type="System.Int32" DbType="Int" />
14 </Function>

　　这就是说，原本这个存储过程会返回一个结果集的，但LINQ会误认为返回的是一个Int32的值。

　　遇到这种情况，我们该怎么处理呢？这里提供两种解决方案：

　　1、直接更改DBML文件，将返回值改成一个空的结果集。

1 <Function Name="dbo.GetEmployeesByFilter" Method="GetEmployeesByFilter">
2 <Parameter Name="EmployeeNo" Parameter="employeeNo" Type="System.String" DbType="NVarChar(50)" />
3 <Parameter Name="EmployeeName" Parameter="employeeName" Type="System.String" DbType="NVarChar(50)" />
4 <Parameter Name="DepartmentId" Parameter="departmentId" Type="System.Int32" DbType="Int" />
5 <Parameter Name="PositionId" Parameter="positionId" Type="System.Int32" DbType="Int" />
6 <Parameter Name="EmployeeManager" Parameter="employeeManager" Type="System.Int32" DbType="Int" />
7 <Parameter Name="BeginEmployeeEntryDate" Parameter="beginEmployeeEntryDate" Type="System.DateTime" DbType="DateTime" />
8 <Parameter Name="EndEmployeeEntryDate" Parameter="endEmployeeEntryDate" Type="System.DateTime" DbType="DateTime" />
9 <Parameter Name="EmployeeStatus" Parameter="employeeStatus" Type="System.Int32>" DbType="Int" />
10 <Parameter Name="PageSize" Parameter="pageSize" Type="System.Int32" DbType="Int" />
11 <Parameter Name="PageIndex" Parameter="pageIndex" Type="System.Int32" DbType="Int" />
12 <Parameter Name="RecordCount" Parameter="recordCount" Type="System.Int32" DbType="Int" Direction="InOut" />
13 <ElementType Name="GetEmployeesByFilterResult" />
14 </Function>

　　然后再按照上一篇文章所说的方法处理即可。

　　2、保持存储过程GetEmployeesByFilter不变，再创建另外一个存储过程GetEmployeesByFilterCalling，然后在存储过程GetEmployeesByFilterCalling中调用存储过程GetEmployeesByFilter（EXEC GetEmployeesByFilter）。

　　（感谢Microsoft公司的Brandon Wang提供的这个方案。不过对不住的是，在我的系统中第一种方案用起来似乎更为方便些。）
本文出自 “Denny_Zhang” 博客，出处/article/4408072.html

posted on 2009-05-07 11:44 瞌睡