Question

我有一个将数据从SQL数据库绑定到gridview的功能。到目前为止，它运用良好：

    Dim dad As SqlDataAdapter
    Dim bs As BindingSource
    Dim dtb As DataTable
    Private Sub getDataSQL(ByVal selectCommand As String, ByVal connectionString As String)
        dtb = New DataTable
        Dim cnn As New SqlConnection(connectionString)
        cnn.Open()
        dad = New SqlDataAdapter(selectCommand, cnn)
        Dim basiccommands = New SqlCommandBuilder(dad)
        dad.InsertCommand = basiccommands.GetInsertCommand
        dad.UpdateCommand = basiccommands.GetUpdateCommand
        dad.DeleteCommand = basiccommands.GetDeleteCommand
        dad.Fill(dtb)
        bs = New BindingSource
        bs.DataSource = dtb
        navigator_main.BindingSource = bs 'this is a binding navigator
        dgv_main.DataSource = bs 'this is the main datagridview
        cnn.Close()
    End Sub

当用户添加/编辑/删除我调用的行时：

bs.EndEdit()
dad.Update(dtb)

现在我必须重用getData函数，通过连接到不同类型的数据库（主要是MySQL，ODB，SQL）来填充gridview。为此，我创建了一个接口，允许通过指示连接类型重用大量函数：

Public Interface IDataBaseHelper
    Function openConnection(ByVal conn_string As String) As Boolean
    Function executeQuery(ByVal query As String) As IDataReader
    Function executeQuery(ByVal command As IDbCommand) As IDataReader
    Function executeNonQuery(ByVal query As String) As Integer
    Function createSQLCommand(ByVal query As String) As IDbCommand
    Function getDataAdapter(ByVal query As String) As IDataAdapter
    Sub closeConnection()
End Interface

新功能如下所示：

    Private mBindingSource As New BindingSource()
    Private mDataAdapter As IDataAdapter
    Private mDataSet As DataSet
    Private Sub getData(ByVal selectCommand As String, ByVal connectionString As String, ByVal connectionType As String)
        'Connection types are defined in FDataBaseHelper: FDataBaseHelper.SQLSERVER_ .MYSQL_ .ODBC_
        Dim cnn = FDataBaseHelper.createInstance(connectionType)
        cnn.openConnection(connectionString)
        mDataAdapter = cnn.getDataAdapter(selectCommand)
        mDataSet = New DataSet()
        Dim dtb As New DataTable
        mDataAdapter.Fill(mDataSet)
        dtb = mDataSet.Tables(0)
        mBindingSource.DataSource = dtb
        navigator_main.BindingSource = mBindingSource
        dgv_main.DataSource = mBindingSource
    End Sub

clase FDataBaseHelper看起来像：

Public Class FDataBaseHelper
    'Class factory depending on type of connection
    Public Const SQLSERVER_ = "SQLServer"
    Public Const MYSQL_ = "MySQL"
    Public Const ODBC_ = "ODBC"

    Public Shared Function createInstance(conn_type As String) As IDataBaseHelper
        If conn_type = SQLSERVER_ Then
            Return New DataBaseHelperSQL
        ElseIf conn_type = MYSQL_ Then
            Return New DataBaseHelperMySQL
        ElseIf conn_type = ODBC_ Then
            Return New DataBaseHelperODBC
        End If
        Return Nothing
    End Function

End Class

getDataAdapter函数（例如DataBaseHelperSQL）是：

Public Function getDataAdapter(query As String) As IDataAdapter Implements IDataBaseHelper.getDataAdapter
        Dim command = createSQLCommand(query)
        Dim adapter = New SqlDataAdapter(command)
        Return adapter
    End Function

datagridview很好地填充，但用户所做的任何更改都不会存储在数据库中。问题是IDataAdapter没有InsertCommand，UpdateCommand和DeleteCommand作为成员，我收到错误：

mAdapter.Update(mDataSet)

错误说：“当使用新行传递DataRow集合时，更新需要有效的InsertCommand” 我已经尝试了几个建议的解决方案，但无济于事，因为我没有发现任何人使用接口。任何帮助将不胜感激

编辑：最后，解决方案就像在辅助类中移动基本命令的定义一样简单。例如。对于DataBaseHelperSQL，getDataAdapter方法代表：

Public Function getDataAdapter(query As String) As IDataAdapter Implements IDataBaseHelper.getDataAdapter
        Dim command = createSQLCommand(query)
        Dim adapter = New SqlDataAdapter(command)
        Dim basiccommands = New SqlCommandBuilder(adapter)
        adapter.InsertCommand = basiccommands.GetInsertCommand
        adapter.UpdateCommand = basiccommands.GetUpdateCommand
        adapter.DeleteCommand = basiccommands.GetDeleteCommand
            Return adapter
End Function

Answer 1

最后，解决方案就像在辅助类中移动基本命令的定义一样简单。例如。对于DataBaseHelperSQL，getDataAdapter方法代表：

Public Function getDataAdapter(query As String) As IDataAdapter Implements IDataBaseHelper.getDataAdapter
        Dim command = createSQLCommand(query)
        Dim adapter = New SqlDataAdapter(command)
        Dim basiccommands = New SqlCommandBuilder(adapter)
        adapter.InsertCommand = basiccommands.GetInsertCommand
        adapter.UpdateCommand = basiccommands.GetUpdateCommand
        adapter.DeleteCommand = basiccommands.GetDeleteCommand
            Return adapter
End Function

IDataAdapter和基本命令（插入，更新，删除）

1 个答案: