使用 XML 和 Visual Basic .NET 将值数组传递到SQL Server存储过程

本文介绍如何使用 XML 和 Visual Basic .NET 将值数组传递到SQL Server存储过程。

原始产品版本： Visual Basic
原始 KB 编号： 555266

症状

需要将值数组传递到SQL Server存储过程，以将其用作子句的列表IN。

原因

当前版本的 Microsoft SQL Server不支持允许将值数组作为存储过程或 SQL 语句的参数传递的数组数据类型。 通常，开发人员需要传递值数组，以便根据子句中 IN 提供的列表选择记录。 在某些情况下，以逗号分隔的字符串形式传递给存储过程的参数列表，此分隔字符串不能直接用作 IN 子句的参数，并且必须转换为在 子句内 IN 使用时可接受的形式。

解决方案

此问题的解决方案之一是将值的数组作为 XML 字符串参数传递给存储过程，并在存储过程内部使用 OPENXML rowset 提供程序从提供的 XML 中选择值。 OPENXML将 提供程序与 Transact-SQL 语句结合使用可提供灵活且简单的方法来根据传递的值数组操作数据库中的数据。

创建项目

我们将使用 SQL Server 数据库中的 Northwind Orders 表。 使用以下强在数据库中创建存储过程 Northwind 。

IF EXISTS (SELECT name
    FROM sysobjects
    WHERE name = N'sp_SelectOrders'
    AND type = 'P')
    DROP PROCEDURE sp_SelectOrders
GO

CREATE PROC sp_SelectOrders @in_values nText AS

DECLARE @hDoc int

--Prepare input values as an XML documnet
exec sp_xml_preparedocument @hDoc OUTPUT, @in_values

--Select data from the table based on values in XML
SELECT * FROM Orders WHERE CustomerID IN (
 SELECT CustomerID FROM OPENXML (@hdoc, '/NewDataSet/Customers', 1)
 WITH (CustomerID NCHAR(5)))

EXEC sp_xml_removedocument @hDoc

GO

启动 Visual Studio .NET 并创建控制台应用程序。 默认情况下，将创建 Module1.vb 文件。

将 Module1.vb 文件中的 强 替换为以下文件。 为了简化和示例，sample strong 从“客户”表中选择所有客户的列表，仅为一半 (的客户的 XML 字符串准备值数组，以演示) 有限选择，然后运行存储过程，从所选客户的“订单”表中选择订单列表。

Imports System.Data.SqlClient
Imports System.Xml
Imports System.Text

Module Module1

PublicSub Main()

    Dim loCustomers As DataSet
    Dim loOrders As DataTable
    
    Try
    
        'Get list of the customers from the database
        loCustomers = GetCustomers()
        
        Console.WriteLine("Total customers: " & loCustomers.Tables(0).Rows.Count.ToString)
        
        If Not loCustomers Is Nothing Then
            loOrders = GetOrders(loCustomers)
            Console.WriteLine("Total orders: " & loOrders.Rows.Count.ToString)
        EndIf
        
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        Finally
        
        If Not loCustomers Is Nothing Then
            loCustomers.Dispose()
            loCustomers = Nothing
        EndIf
        
        If Not loOrders Is Nothing Then
            loOrders.Dispose()
            loOrders = Nothing
        EndIf
    
    EndTry

EndSub

Private Function GetOrders(ByVal loCustomers As DataSet) As DataTable

    Dim loOrders As DataSet
    Dim loParameter As SqlParameter
    Dim loCol As DataColumn
    
    Try
    
        'Prepare XML output from the Customers DataSet as a string
        ForEach loCol In loCustomers.Tables("Customers").Columns
            loCol.ColumnMapping = System.Data.MappingType.Attribute
        Next
        
        'Pass XML into the stored procedure as a parameter
        loParameter = New SqlParameter("@in_values", System.Data.SqlDbType.NText)
        loParameter.Value = loCustomers.GetXml
        
        'Get list of the orders from the database
        loOrders = GetDataFromDb("sp_SelectOrders", CommandType.StoredProcedure, "Customers", loParameter)'Return list of the orders as a DataTable
        If (Not loOrders Is Nothing) AndAlso loOrders.Tables.Count = 1 Then
            Return loOrders.Tables(0)
        EndIf
    
    Catch ex As Exception
        Throw ex
    EndTry

EndFunction

Private Function GetCustomers() As DataSet

    Dim loCustomers As DataSet
    Dim i As Int32
    
    Try
    
    'Get list of the customers from the database
    loCustomers = GetDataFromDb("SELECT CustomerID FROM Customers", CommandType.Text, "Customers")'Remove half of the customers for the demo purposes to show that we select info just for some of them
    If Not loCustomers Is Nothing Then
    
    If loCustomers.Tables.Contains("Customers") Then
            With loCustomers.Tables("Customers")
        
        i = .Rows.Count \ 2
        DoWhile .Rows.Count > i
            .Rows.RemoveAt(0)
        Loop
        
        'Accept changes to remove the rows completely from the DataTable
        .AcceptChanges()
        EndWith
        Else
            ThrowNew ApplicationException("Customers table does not exist")
        EndIf
    
    EndIf
    
    'Return list of the customers as a DataSet
    Return loCustomers
    
    Catch ex As Exception
        Throw ex
    EndTry

EndFunction

Private Function GetDataFromDb(ByVal lcSQL AsString, ByVal loCommandType As CommandType, _
ByVal lcTableName AsString, ByValParamArray loParameters() As SqlParameter) As DataSet

    Dim loResult As DataSet
    Dim loConnection As SqlConnection
    Dim loCommand As SqlCommand
    Dim loAdapter As SqlDataAdapter
    Dim i As Int32
    Dim loParameter As SqlParameter
    
    Try
    
        'Create and open connection to the Northwind database
        loConnection = New SqlConnection("Persist Security Info=False;Integrated Security=SSPI;database=northwind;server=(local);Connect Timeout=30")
        loConnection.Open()'Prepare command and to select data from the database
        loCommand = New SqlCommand(lcSQL, loConnection)
        loCommand.CommandType = loCommandType
        
        IfNot loParameters IsNothingThen
        ForEach loParameter In loParameters
        loCommand.Parameters.Add(loParameter)
        Next
        EndIf
        
        loAdapter = New SqlDataAdapter(loCommand)
        
        loResult = New DataSet
        loAdapter.Fill(loResult, lcTableName)'Return list of the customers as a DataSet
        Return loResult
    
    Catch ex As Exception
        Throw ex
    Finally
    
        'Clean resources
        If Not loAdapter Is Nothing Then
            loAdapter.Dispose()
            loAdapter = Nothing
        EndIf
        
        If Not loCommand Is Nothing Then
            loCommand.Dispose()
            loCommand = Nothing
        EndIf
        
        If Not loConnection Is Nothing Then
        
            If loConnection.State = ConnectionState.Open Then
                loConnection.Close()
            EndIf
            
            loConnection.Dispose()
            loConnection = Nothing
        
        EndIf
    EndTry

  EndFunction

EndModule

按 F5 编译并运行应用程序。 控制台将显示结果。