IDbDataAdapter.SelectCommand 属性
定义
重要
一些信息与预发行产品相关,相应产品在发行之前可能会进行重大修改。 对于此处提供的信息,Microsoft 不作任何明示或暗示的担保。
获取或设置用于在数据源中选择记录的 SQL 语句。
public:
property System::Data::IDbCommand ^ SelectCommand { System::Data::IDbCommand ^ get(); void set(System::Data::IDbCommand ^ value); };
public System.Data.IDbCommand? SelectCommand { get; set; }
public System.Data.IDbCommand SelectCommand { get; set; }
member this.SelectCommand : System.Data.IDbCommand with get, set
Public Property SelectCommand As IDbCommand
属性值
在 IDbCommand 过程中使用的 Update(DataSet),它从数据源中选择记录以便放入数据集中。
示例
以下示例创建继承 OleDbDataAdapter 类的实例,并设置 SelectCommand 和 InsertCommand 属性。 它假定你已创建对象 OleDbConnection 。
public static OleDbDataAdapter CreateCustomerAdapter(
OleDbConnection connection)
{
OleDbDataAdapter adapter = new OleDbDataAdapter();
OleDbCommand command;
// Create the SelectCommand.
command = new OleDbCommand("SELECT * FROM Customers " +
"WHERE Country = ? AND City = ?", connection);
command.Parameters.Add("Country", OleDbType.VarChar, 15);
command.Parameters.Add("City", OleDbType.VarChar, 15);
adapter.SelectCommand = command;
// Create the InsertCommand.
command = new OleDbCommand(
"INSERT INTO Customers (CustomerID, CompanyName) " +
"VALUES (?, ?)", connection);
command.Parameters.Add(
"CustomerID", OleDbType.Char, 5, "CustomerID");
command.Parameters.Add(
"CompanyName", OleDbType.VarChar, 40, "CompanyName");
adapter.InsertCommand = command;
return adapter;
}
Public Shared Function CreateCustomerAdapter( _
connection As OleDbConnection) As OleDbDataAdapter
Dim adapter As New OleDbDataAdapter()
Dim command As OleDbCommand
' Create the SelectCommand.
command = New OleDbCommand("SELECT * FROM Customers " & _
"WHERE Country = ? AND City = ?", connection)
command.Parameters.Add("Country", OleDbType.VarChar, 15)
command.Parameters.Add("City", OleDbType.VarChar, 15)
adapter.SelectCommand = command
' Create the InsertCommand.
command = New OleDbCommand( _
"INSERT INTO Customers (CustomerID, CompanyName) " & _
"VALUES (?, ?)", connection)
command.Parameters.Add( _
"CustomerID", OleDbType.Char, 5, "CustomerID")
command.Parameters.Add( _
"CompanyName", OleDbType.VarChar, 40, "CompanyName")
adapter.InsertCommand = command
Return adapter
End Function
注解
当 SelectCommand 分配给之前创建的 IDbCommand时, IDbCommand 不会克隆 。 维护 SelectCommand 对以前创建的 IDbCommand 对象的引用。
SelectCommand如果 不返回任何行,则不会向 DataSet添加任何表,并且不会引发异常。