Question

我在模块中创建了一个函数来连接到Windows应用程序的数据库

Imports System.Data.SqlClient
Module mod_main
Public Function connectDB() As SqlConnection
        Dim Connection As New SqlConnection
        Try
            If Connection.State = ConnectionState.Open Then
                Connection.Close()
            End If
            If IntegratedSecurity Then
                Connection.ConnectionString = "Data Source = " & server & ";Initial Catalog = " & db & ";Connection TimeOut =0;Integrated Security=True"
            Else
                Connection.ConnectionString = "Data Source = " & server & ";Initial Catalog = " & db & ";Connection TimeOut =0;User ID='" & usr & "';Password='" & pwd & "'"
            End If
            Connection.Open()
            Return Connection
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End Function
End Module

我有很多函数和类使用了大量的db活动，因为我使用了上面提到的连接函数。例如：

 Public Sub FillComboBox(ByVal ComboBox As C1.Win.C1List.C1Combo, ByVal Query As String, ByVal DisplayMember As String, ByVal ValueMember As String)
        Dim SourceDataSet As New DataSet
        Dim adapter As New SqlDataAdapter(Query, connectDB) /*Assigning connection here */
        adapter.Fill(SourceDataSet)
        ComboBox.DataSource = SourceDataSet.Tables(0)
        ComboBox.ColumnHeaders = False
        ComboBox.ColumnWidth = 0
        ComboBox.ExtendRightColumn = True
        ComboBox.DisplayMember = DisplayMember
        ComboBox.ValueMember = ValueMember
    End Sub

由于我是编程的初学者，我的问题是，这是处理数据库连接的正确方法吗？

Answer 1

我建议您进行以下更改：

将Connection公开为全球可访问性
在config file中保存连接字符串并从那里访问
仅在没有可用连接时才需要关闭并重新打开连接打开连接

在您的情况下，它始终在函数创建新连接时因为你在声明和初始化连接内部而调用了功能。所以检查连接状态意味着更少：

所以你的功能如下：

public Connection As New SqlConnection
Public Function connectDB() As SqlConnection
      Try
            Dim Constr As String =""
            If IntegratedSecurity Then
               Constr = ConfigurationManager.AppSetting("IconnectionString")
            Else
               Constr  = ConfigurationManager.AppSetting("connectionString")
            End If
            If Connection Is Nothing Then
                Connection = New SqlConnection(Constr)
            End If
            If Connection.State <> ConnectionState.Open Then
              Connection.Open()
            End If           
            Return Connection
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
End Function

如何在整个项目中处理数据库连接

1 个答案: