如何仅从数据集中返回一条记录 [英] How to return only one record from a dataset

问题描述

大家好，

我对数据集有疑问.

如何从具有多个记录的数据集中仅返回一条记录.

如果有人可以帮助我，那就太好了！这是我的预先代码.如果有帮助，我目前正在使用VS2010.

谢谢

Hello everyone,

I have a question regarding a dataset.

How do I return only one record from a dataset that has mulitple records.

If anyone can help me, that would be great! Here is my code in advance. I am currently using VS 2010 if that helps.

Thank you

Public Function ReadPolicyStep1(ByVal custnum As String, ByVal symb0l As String, ByVal policynum As String) As DataSet 

  Dim con As OdbcConnection = New OdbcConnection(_connString)
  Dim cmd As OdbcCommand = New OdbcCommand("SELECT CUST0NO, SYMBOL, POLICY0NUM, MODULE, TYPE0ACT FROM CCC00200 WHERE CUST0NO = ? AND SYMBOL = ? AND POLICY0NUM = ? ORDER BY MODULE DESC", con)

            cmd.Parameters.AddWithValue("@custnum", custnum)
            cmd.Parameters.AddWithValue("@symb0l", symb0l)
            cmd.Parameters.AddWithValue("@policynum", policynum)

            cmd.CommandType = CommandType.Text 

            Dim da As New OdbcDataAdapter(cmd)
            Dim ds As New DataSet() 

            Using da
               da.Fill(ds)
            End Using 

            Return ds 

        End Function

[edit]已添加代码块-OriginalGriff [/edit]

[edit]Code block added - OriginalGriff[/edit]

推荐答案

尝试:

SELECT TOP 1 CUST0NO, SYMBOL, POLICY0NUM, MODULE, TYPE0ACT FROM CCC00200 WHERE CUST0NO = ? AND SYMBOL = ? AND POLICY0NUM = ? ORDER BY MODULE DESC

HI ...

试试这个代码...

HI...

Try this code...

Public Function ReadPolicyStep1(ByVal custnum As String, ByVal symb0l As String, ByVal policynum As String) As DataRow

    Dim con As OdbcConnection = New OdbcConnection(_connString)
    Dim cmd As OdbcCommand = New OdbcCommand("SELECT CUST0NO, SYMBOL, POLICY0NUM, MODULE, TYPE0ACT FROM CCC00200 WHERE CUST0NO = ? AND SYMBOL = ? AND POLICY0NUM = ? ORDER BY MODULE DESC", con)

    cmd.Parameters.AddWithValue("@custnum", custnum)
    cmd.Parameters.AddWithValue("@symb0l", symb0l)
    cmd.Parameters.AddWithValue("@policynum", policynum)

    cmd.CommandType = CommandType.Text

    Dim da As New OdbcDataAdapter(cmd)
    Dim ds As New DataSet()

    Using da
        da.Fill(ds)
    End Using

   If ds.Tables(0).Rows.Count > 0 Then
        Return Nothing
    Else
        Return ds.Tables(0).Rows(0)
    End If

End Function

Dim cmd As OdbcCommand = New OdbcCommand("SELECT top 1 CUST0NO, SYMBOL, POLICY0NUM, MODULE, TYPE0ACT FROM CCC00200 WHERE CUST0NO = ? AND SYMBOL = ? AND POLICY0NUM = ? ORDER BY MODULE DESC", con)

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