连接DB的各种方式

     Private Function sql_Connection() As SqlConnection
        Dim SqlConnection As New SqlConnection()
        Dim ConnectionString As String = "Data Source=192.168.88.135;Initial Catalog=MC5;Persist Security Info=True;User ID=MC5;Password=MC5"
        SqlConnection.ConnectionString = ConnectionString
        Try
            SqlConnection.Open()
            Return SqlConnection

        Catch ex As Exception
            MsgBox(Err.Description)

        End Try
        Return SqlConnection
    End Function
    Private Function SqlSelect() As DataSet
        Dim sqlConnection As SqlConnection
        Dim dbCommand As New SqlCommand
        Dim DataAdapter As New SqlDataAdapter
        Dim dataset As New DataSet
        Dim dataRead As SqlDataReader
        Dim strSelect As String = "select * from page_tbl"

        sqlConnection = sql_Connection()
        DataAdapter.SelectCommand = New SqlCommand(strSelect, sqlConnection)
        DataAdapter.Fill(dataset, "page_tbl")
        dataRead = DataAdapter.SelectCommand.ExecuteReader()

        dbCommand.CommandText = strSelect
        dbCommand.CommandType = CommandType.Text
        dbCommand.Connection = sqlConnection
        Try
            dataRead = dbCommand.ExecuteReader()

        Catch ex As Exception
            MsgBox(Err.Description)
        Finally
            sqlConnection.Close()
            sqlConnection.Dispose()
        End Try

        Return dataset

    End Function

    Private Function sqlConnection() As OleDbConnection
        Dim conn As String = "Provider=SQLOLEDB;Data Source=192.168.88.135;Initial Catalog=MC5;sever=localhost;User Id=MC5;Password=MC5;"
        Dim dbConnection As OleDbConnection
        dbConnection = New OleDbConnection(conn)
        Try
            dbConnection.Open()
        Catch EX As Exception
            MsgBox(Err.Description)
        End Try
        Return dbConnection
    End Function
    Private Function getConnection() As OleDbConnection
        Dim conn As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=F:/MC5/MC5Log/MC5DB.mdb;Persist Security Info=False"
        Dim dbConnection As OleDbConnection
        dbConnection = New OleDbConnection(conn)
        Try
            dbConnection.Open()
        Catch EX As Exception
            MsgBox(Err.Description)
        End Try
        Return dbConnection

    End Function

    Private Function AccessSlect() As DataSet
        Dim dbConnection As OleDbConnection
        Dim dbAdapter As New OleDbDataAdapter
        Dim dataSet As New DataSet
        Dim sqlSelect As String = "select * from dir_tbl"
        dbConnection = getConnection()
        dbAdapter.SelectCommand = New OleDbCommand(sqlSelect, dbConnection)
        Try
            dbAdapter.Fill(dataSet, "dir_tbl")
        Catch ex As Exception
            MsgBox(Err.Description)
        Finally
            AccessSlect = dataSet
            dataSet.Dispose()
            dbAdapter.Dispose()
            dbConnection.Close()
            dbConnection.Dispose()
        End Try

    End Function
    Private Function AccessUpdate() As Boolean
        Dim dbConnection As OleDbConnection
        Dim dbAdapter As New OleDbDataAdapter
        Dim sqlupdate As String = "update dir_tbl set file_name ='123'"
        dbConnection = getConnection()
        dbAdapter.UpdateCommand = New OleDbCommand(sqlupdate, dbConnection)
        Try
            dbAdapter.UpdateCommand.ExecuteNonQuery()
            AccessUpdate = True
        Catch ex As Exception
            MsgBox(Err.Description)
            AccessUpdate = False
        Finally
            dbAdapter.Dispose()
            dbConnection.Close()
            dbConnection.Dispose()

        End Try

    End Function
    Private Function AccessInsert() As Boolean
        Dim dbConnection As OleDbConnection
        Dim dbAdapter As New OleDbDataAdapter
        Dim sqlInsert As String = "insert into dir_tbl values('12346','456','789')"
        dbConnection = getConnection()
        dbAdapter.InsertCommand = New OleDbCommand(sqlInsert, dbConnection)
        Try
            dbAdapter.InsertCommand.ExecuteNonQuery()
            AccessInsert = True
        Catch ex As Exception
            MsgBox(Err.Description)
            AccessInsert = True
        Finally
            dbAdapter.Dispose()
            dbConnection.Close()
            dbConnection.Dispose()

        End Try

    End Function
    Private Function AccessDelete() As Boolean
        Dim dbConnection As OleDbConnection
        Dim dbCommand As New OleDbCommand
        dbConnection = getConnection()
        dbCommand.CommandText = "delete  from dir_tbl"
        dbCommand.Connection = dbConnection
        Try
            dbCommand.ExecuteNonQuery()

        Catch ex As Exception
            MsgBox(Err.Description)
        Finally
            dbCommand.Dispose()
            dbConnection.Close()
            dbConnection.Dispose()

        End Try

    End Function