带有来自 vb.net 的参数的 postgreSQL 查询

Question

我正在尝试编写一个选择语句 (postgreSQL)，它使用我的应用程序屏幕中的一个字段。

我已经 2 天没有成功。 任何帮助和/或解释等......将不胜感激。

下面是整个子​​。 （代码尚未完成、优化或测试，请原谅任何糟糕的编码） 在以下行收到错误：ODBCdaDups.Fill(dsDups2) 收到的错误是：ERROR [42883] ERROR: operator does not exist:@text; & vblf & "执行查询时出错" 我尝试使用编号参数（$1、$2 等），但也无法弄清楚。

Private Sub Check4Duplicate()
    Dim DupMessage As String
    Try
        Dim DupSQL As String = Nothing
        Dim DupConn As New OdbcConnection()
        Dim strConn As String = ""
        If GlobalVariables.logProd = 1 Then
            strConn = "Driver={PostgreSQL ANSI};database=SacredSelections;server=127.0.0.1;port=5432;uid=SSApp;sslmode=disable;readonly=0;protocol=7.4;User ID=SSApp;password=Cordova123;"
        Else
            strConn = "Driver={PostgreSQL ANSI};database=SacredSelectionsTest;server=127.0.0.1;port=5432;uid=SSApp;sslmode=disable;readonly=0;protocol=7.4;User ID=SSApp;password=Cordova123;"
        End If
        Dim dsDups2 As New DataSet
        Dim ODBCdaDups As OdbcDataAdapter
        Dim cmdbldDups As OdbcCommandBuilder
        Dim cmdDups As OdbcCommand
        DupConn = New OdbcConnection(strConn)
        DupConn.Open()
        dsDups2 = New DataSet
        ODBCdaDups = New OdbcDataAdapter
        cmdbldDups = New OdbcCommandBuilder(ODBCdaDups)
        dsDups2.DataSetName = "auctions"

        ' Create the SelectCommand.
        ' Original SQL Server command
        'cmdDups = New OdbcCommand("Select * From auctions where auction_name = @auction_name;", DupConn)
        ' Trying to create new postgresql command
        cmdDups = New OdbcCommand("do $$
        begin
          select *
          from auctions
          where auction_name = @auction_name;
        end;
        $$
        ", DupConn)
        cmdDups.Parameters.Add("auction_name", SqlDbType.Text).Value = txt_auction_name.Text
        cmdDups.Prepare()
        ODBCdaDups.SelectCommand = cmdDups
        ODBCdaDups.Fill(dsDups2)
        DupConn.Close()

        If Not DupConn Is Nothing Then DupConn.Dispose()

        DupMessage = ""
        ' Loop over tables in the DataSet.
        Dim collection As DataTableCollection = dsDups2.Tables
        If dsDups2.Tables(0).Rows.Count = 0 Then
            DupTitle = "Unique Record - Save Allowed"
            If strEditType = "Edit" Then
                DupMessage = "This will save changes to an existing Unique record for Auction ID " + txt_auction_id.Text + " and Auction Name " + txt_auction_name.Text + " and Location Name " + txt_location_address.Text
            Else
                DupMessage = "This will create a Unique record for Auction ID " + txt_auction_id.Text + " and Auction Name " + txt_auction_name.Text + " and Location Name " + txt_location_address.Text
            End If
        Else
            DupTitle = "Duplicate Record - Save NOT Allowed"
            DupMessage = "A record already exists with Auction ID " + txt_auction_id.Text + " and Auction Name " + txt_auction_name.Text + " and Location Name " + txt_location_address.Text
            MessageBox.Show(DupMessage, DupTitle)
        End If

    Catch ex As Exception
        DupTitle = "Connection failed"
        DupMessage = "Unable to Open Auction Information Connection to check for Existing Records"
        MessageBox.Show(DupMessage, DupTitle)
    End Try
End Sub

Answer 1

ODBC 中的参数名称无关紧要。重要的是参数出现在 sql 命令中的顺序必须与它们添加到 ParametersCollection 的顺序相匹配。

Using...End Using 阻止关闭和处置数据库对象，即使出现错误。

我不得不猜测字段名称和数据类型，因此请检查您的数据库中的实际值并相应地调整您的代码。如果任何字段是数字类型，您将不会将文本框的 .Text 属性转换为正确的类型。

通常主键字段永远不会更新，因此请从代码中删除 PK 字段的更新。如果一个字段是自动递增的，您将不会为该字段插入一个值。通过删除自动编号字段中的任何插入来调整代码。

Private Function GetConnectionString() As String
    Dim strConn As String
    If GlobalVariables.logProd = 1 Then
        strConn = "Driver={PostgreSQL ANSI};database=SacredSelections;server=127.0.0.1;port=5432;uid=SSApp;sslmode=disable;readonly=0;protocol=7.4;User ID=SSApp;password=Cordova123;"
    Else
        strConn = "Driver={PostgreSQL ANSI};database=SacredSelectionsTest;server=127.0.0.1;port=5432;uid=SSApp;sslmode=disable;readonly=0;protocol=7.4;User ID=SSApp;password=Cordova123;"
    End If
    Return strConn
End Function

Private Sub Check4Duplicate(strEditType As String)
    Dim DupMessage As String
    Dim DupTitle As String
    Try
        Dim dt As New DataTable
        Using DupConn As New OdbcConnection(GetConnectionString())
            Using cmdDups As New OdbcCommand("select auction_name from auctions where auction_name = ?;", DupConn)
                cmdDups.Parameters.Add("@auction_name", OdbcType.VarChar).Value = txt_auction_name.Text
                dt.Load(cmdDups.ExecuteReader)
            End Using
        End Using

        If dt.Rows.Count = 0 Then
            DupTitle = "Unique Record - Save Allowed"
            If strEditType = "Edit" Then
                DupMessage = "This will save changes to an existing Unique record for Auction ID " + txt_auction_id.Text + " and Auction Name " + txt_auction_name.Text + " and Location Name " + txt_location_address.Text
                UpdateAuction()
            Else
                DupMessage = "This will create a Unique record for Auction ID " + txt_auction_id.Text + " and Auction Name " + txt_auction_name.Text + " and Location Name " + txt_location_address.Text
                InsertAuction()
            End If
        Else
            DupTitle = "Duplicate Record - Save NOT Allowed"
            DupMessage = $"A record already exists with Auction ID {txt_auction_id.Text} and Auction Name {txt_auction_name.Text} and Location Name {txt_location_address.Text}"
            MessageBox.Show(DupMessage, DupTitle)
        End If
    Catch ex As Exception
        DupTitle = "Connection failed"
        DupMessage = "Unable to Open Auction Information Connection to check for Existing Records"
        MessageBox.Show(DupMessage, DupTitle)
    End Try
End Sub

Private Sub InsertAuction()
    Using DupConn As New OdbcConnection(GetConnectionString())
        Using cmd As New OdbcCommand("Insert Into auctions (auction_id, auction_name, auction_address) Values (?,?,?)")
            cmd.Parameters.Add("id", OdbcType.VarChar).Value = txt_auction_id.Text
            cmd.Parameters.Add("name", OdbcType.VarChar).Value = txt_auction_name.Text
            cmd.Parameters.Add("address", OdbcType.VarChar).Value = txt_location_address.Text
            DupConn.Open()
            cmd.ExecuteNonQuery()
        End Using
    End Using
End Sub

Private Sub UpdateAuction()
    Using DupConn As New OdbcConnection(GetConnectionString())
        Using cmd As New OdbcCommand("Update auctions Set auction_id = ?, auction_name = ?, auction_address = ? Where aution_name = ?")
            cmd.Parameters.Add("id", OdbcType.VarChar).Value = txt_auction_id.Text
            cmd.Parameters.Add("name", OdbcType.VarChar).Value = txt_auction_name.Text
            cmd.Parameters.Add("address", OdbcType.VarChar).Value = txt_location_address.Text
            cmd.Parameters.Add("name2", OdbcType.VarChar).Value = txt_auction_name.Text
            DupConn.Open()
            cmd.ExecuteNonQuery()
        End Using
    End Using
End Sub

这似乎是重复构建连接和命令的代码重复，但将这些项目保留在使用它们的方法的本地允许我们确保它们已关闭和处置。