Question

从阅读器循环查询数据库时遇到问题：

    Using cn As NpgsqlConnection = getConnection()
        Using t As NpgsqlTransaction = cn.BeginTransaction()
           Using cmd As New NpgsqlCommand("SELECT tab_id, i1, d1, rez1, b FROM " & myfirstTable & " WHERE bdoc='" & bdoc.ToString & "' ORDER BY b", cn)
                Using reader1 As NpgsqlDataReader = cmd.ExecuteReader()

    --------------> ''GOES HERE
    |               While (reader1.Read())
    |                   Dim sifra As Integer = CInt(reader1("sifra"))
    | 
    |                       Using icmd As New NpgsqlCommand("SELECT dtbl_id FROM " & mysecondTable & " WHERE dtbl_id>" & firstfree.ToString & " AND kni::int=0 ORDER BY dtbl_id LIMIT 1", cn)
    |               
    --------------------------- ''FROM HERE
                                firstfree = CInt(icmd.ExecuteScalar())
                            End Using ''cmd

                    End While
                End Using ''reader
            End Using ''cmd
            t.Commit()
        End Using
    End Using

当reader's.read循环时，我必须从新查询到数据库获得整数firstfree 通过在pgAdmin中测试，我的命令工作很好但在节目中没有当firstfree = CInt（icmd.ExecuteScalar（））将要执行''FROM HERE程序跳转到新的循环步骤''GOES HERE

这里明显不正确的事情以及如何使其发挥作用？

这是getConnection函数。

Public Function getConnection() As NpgsqlConnection

    Dim chkCon As New NpgsqlConnection(String.Format( _
                      "Server={0};Port={1};User Id={2};Password={3};Database={4};Preload Reader = true;", _
                      dbServer, dbPort, dbUser, dbPass, mydatabase))
    Try
        chkCon.Open()
    Catch ex As Exception
        Return Nothing
    End Try

    Return chkCon
End Function

Answer 1

我看不出你的语言是什么，等等。但在你看来，你的循环中有两个明显的拼写错误。

例如，应该：

 End Using ''cmd

是

 End Using ''icmd

并且应该

 End Using ''reader

是

 End Using ''reader1

无论如何，这看起来像循环语法问题，所以我将调试视为.net问题而不是PostgreSQL问题。

从阅读器循环查询数据库

1 个答案: