ADO.NET对象的构造(7)_OleDbParameter(下)

n Overloads Public Overridable Function Add(ByVal value As Object ) As Integer Implements IList.Add

n Overloads Public Function Add(ByVal parameterName As String ,ByVal value As Object ) As OleDbParameter

n Overloads Public Function Add(ByVal value As OleDbParameter ) As OleDbParameter

n Overloads Public Function Add(ByVal parameterName As String ,ByVal oleDbType As OleDbType ) As OleDbParameter

n Overloads Public Function Add(ByVal parameterName As String ,ByVal oleDbType As OleDbType ,ByVal size As Integer ) As OleDbParameter

n Overloads Public Function Add(ByVal parameterName As String ,ByVal oleDbType As OleDbType ,ByVal size As Integer ,ByVal sourceColumn As String ) As OleDbParameter

示例

Public Sub CreateOleDbParamColl(myConn As OleDbConnection)

Dim myCommand As OleDbCommand = New OleDbCommand("SELECT * FROM Customers WHERE CustomerID = ?", myConn)

Dim myParamCollection As OleDbParameterCollection = myCommand.Parameters

Dim myParm As Object = New OleDbParameter("CustomerID", OleDbType.VarChar)

Dim pIndex As Integer = myParamCollection.Add(myParm)

Dim myParm As OleDbParameter = myParamCollection.Add( New OleDbParameter ("CustomerID", OleDbType.VarChar))

Dim myParm As OleDbParameter = myParamCollection.Add("CustomerID", “CustomerIDValue”);

Dim myParm As OleDbParameter = myParamCollection.Add("CustomerID", OleDbType.VarChar)

Dim myParm As OleDbParameter = myParamCollection.Add("CustomerID", OleDbType.VarChar, 5)

Dim myParm As OleDbParameter = myParamCollection.Add("CustomerID", OleDbType.VarChar, 5, "CustomerID")

End Sub

示例

Public Shared Function CreateCustomerAdapter(conn As OleDbConnection) As OleDbDataAdapter

Dim da As OleDbDataAdapter = New OleDbDataAdapter()

Dim cmd As OleDbCommand

Dim parm As OleDbParameter

' Create the SelectCommand.

cmd = New OleDbCommand("SELECT * FROM Customers WHERE Country = @Country AND City = @City", conn)

cmd.Parameters.Add("@Country", OleDbType.VarChar, 15)

cmd.Parameters.Add("@City", OleDbType.VarChar, 15)

da.SelectCommand = cmd

' Create the InsertCommand.

cmd = New OleDbCommand("INSERT INTO Customers (CustomerID, CompanyName) VALUES (@CustomerID, @CompanyName)", conn)

cmd.Parameters.Add("@CustomerID", OleDbType.Char, 5, "CustomerID")

cmd.Parameters.Add("@CompanyName", OleDbType.VarChar, 40, "CompanyName")

da.InsertCommand = cmd

' Create the DeleteCommand.

cmd = New OleDbCommand("DELETE FROM Customers WHERE CustomerID = @CustomerID", conn)

parm = cmd.Parameters.Add("@CustomerID", OleDbType.Char, 5, "CustomerID")

parm.SourceVersion = DataRowVersion.Original

da.DeleteCommand = cmd

' Create the UpdateCommand.

cmd = New OleDbCommand("UPDATE Customers SET CustomerID = @CustomerID, CompanyName = @CompanyName WHERE CustomerID = @oldCustomerID", conn)

cmd.Parameters.Add("@CustomerID", OleDbType.Char, 5, "CustomerID")

cmd.Parameters.Add("@CompanyName", OleDbType.VarChar, 40, "CompanyName")

parm = cmd.Parameters.Add("@oldCustomerID", OleDbType.Char, 5, "CustomerID")

parm.SourceVersion = DataRowVersion.Original

da.UpdateCommand = cmd

Return da

End Function

以下两行

parm = cmd.Parameters.Add("@CustomerID", OleDbType.Char, 5, "CustomerID")

parm.SourceVersion = DataRowVersion.Original

可以缩写为

cmd.Parameters.Add("@CustomerID", OleDbType.Char, 5, "CustomerID").SourceVersion = DataRowVersion.Original

类似地当添加参数后马上进行设置参数的值时 , 也可以进行类似以下缩写

myDataAdapter.SelectCommand.Parameters.Add("@CategoryName", OleDbType.VarChar, 80).Value = "toasters"

myDataAdapter.SelectCommand.Parameters.Add("@SerialNum", OleDbType.Integer).Value = 239

( 信息整理来自 MSDN)

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