SqlTypes y DataSetSqlTypes and the DataSet

ADO.NET 2.0 incorporó compatibilidad mejorada de tipos con el DataSet mediante el espacio de nombres System.Data.SqlTypes.ADO.NET 2.0 introduced enhanced type support for the DataSet through the System.Data.SqlTypes namespace. Los tipos de System.Data.SqlTypes se han diseñado para proporcionar tipos de datos con la misma semántica y precisión que los de una base de datos SQL Server.The types in System.Data.SqlTypes are designed to provide data types with the same semantics and precision as the data types in a SQL Server database. Cada tipo de datos de System.Data.SqlTypes tiene un tipo de datos equivalente en SQL Server, con la misma representación de datos subyacente.Each data type in System.Data.SqlTypes has an equivalent data type in SQL Server, with the same underlying data representation.

El uso de System.Data.SqlTypes directamente en un DataSet otorga varias ventajas cuando se trabaja con tipos de datos de SQL Server.Using System.Data.SqlTypes directly in a DataSet confers several benefits when working with SQL Server data types. System.Data.SqlTypes admite la misma semántica que los tipos de datos nativos de SQL Server.System.Data.SqlTypes supports the same semantics as SQL Server native data types. La especificación de uno de los System.Data.SqlTypes en la definición de un objeto DataColumn elimina la pérdida de precisión que se produce al convertir tipos de datos decimales o numéricos en uno de los tipos de datos de Common Language Runtime (CLR).Specifying one of the System.Data.SqlTypes in the definition of a DataColumn eliminates the loss of precision that can occur when converting decimal or numeric data types to one of the common language runtime (CLR) data types.

EjemploExample

En el siguiente ejemplo se crea un objeto DataTable, que define explícitamente los tipos de datos DataColumn utilizando System.Data.SqlTypes en lugar de tipos CLR.The following example creates a DataTable object, explicitly defining the DataColumn data types by using System.Data.SqlTypes instead of CLR types. El código llena la DataTable con los datos de la tabla Sales.SalesOrderDetail de la base de datos AdventureWorks de SQL Server.The code fills the DataTable with data from the Sales.SalesOrderDetail table in the AdventureWorks database in SQL Server. El resultado que aparece en la ventana de la consola muestra el tipo de datos de cada columna y los valores recuperados de SQL Server.The output displayed in the console window shows the data type of each column, and the values retrieved from SQL Server.

static private void GetSqlTypesAW(string connectionString)
{
    // Create a DataTable and specify a SqlType
    // for each column.
    DataTable table = new DataTable();
    DataColumn icolumnolumn =
        table.Columns.Add("SalesOrderID", typeof(SqlInt32));
    DataColumn priceColumn =
        table.Columns.Add("UnitPrice", typeof(SqlMoney));
    DataColumn totalColumn =
        table.Columns.Add("LineTotal", typeof(SqlDecimal));
    DataColumn columnModifiedDate =
        table.Columns.Add("ModifiedDate", typeof(SqlDateTime));

    // Open a connection to SQL Server and fill the DataTable
    // with data from the Sales.SalesOrderDetail table
    // in the AdventureWorks sample database.
    using (SqlConnection connection = new SqlConnection(connectionString))
    {
        string queryString =
            "SELECT TOP 5 SalesOrderID, UnitPrice, LineTotal, ModifiedDate "
            + "FROM Sales.SalesOrderDetail WHERE LineTotal < @LineTotal";

        // Create the SqlCommand.
        SqlCommand command = new SqlCommand(queryString, connection);

        // Create the SqlParameter and assign a value.
        SqlParameter parameter =
            new SqlParameter("@LineTotal", SqlDbType.Decimal);
        parameter.Value = 1.5;
        command.Parameters.Add(parameter);

        // Open the connection and load the data.
        connection.Open();
        SqlDataReader reader =
            command.ExecuteReader(CommandBehavior.CloseConnection);
        table.Load(reader);

        // Close the SqlDataReader.
        reader.Close();
    }

    // Display the SqlType of each column.
    Console.WriteLine("Data Types:");
    foreach (DataColumn column in table.Columns)
    {
        Console.WriteLine(" {0} -- {1}",
            column.ColumnName, column.DataType.UnderlyingSystemType);
    }

    // Display the value for each row.
    Console.WriteLine("Values:");
    foreach (DataRow row in table.Rows)
    {
        Console.Write(" {0}, ", row["SalesOrderID"]);
        Console.Write(" {0}, ", row["UnitPrice"]);
        Console.Write(" {0}, ", row["LineTotal"]);
        Console.Write(" {0} ", row["ModifiedDate"]);
        Console.WriteLine();
    }
}
Private Sub GetSqlTypesAW(ByVal connectionString As String)

    ' Create a DataTable and specify the
    ' SqlType for each column.
    Dim table As New DataTable()
    Dim icolumnolumn As DataColumn = _
      table.Columns.Add("SalesOrderID", GetType(SqlInt32))
    Dim priceColumn As DataColumn = _
      table.Columns.Add("UnitPrice", GetType(SqlMoney))
    Dim totalColumn As DataColumn = _
      table.Columns.Add("LineTotal", GetType(SqlDecimal))
    Dim columnModifiedDate As DataColumn = _
      table.Columns.Add("ModifiedDate", GetType(SqlDateTime))

    ' Open a connection to SQL Server and fill the DataTable
    ' with data from the Sales.SalesOrderDetail table
    ' in the AdventureWorks sample database.
    Using connection As New SqlConnection(connectionString)

        Dim queryString As String = _
           "SELECT TOP 5 SalesOrderID, UnitPrice, LineTotal, ModifiedDate " _
           & "FROM Sales.SalesOrderDetail WHERE LineTotal < @LineTotal"

        ' Create the SqlCommand.
        Dim command As SqlCommand = New SqlCommand(queryString, connection)

        ' Create the SqlParameter and assign a value.
        Dim parameter As SqlParameter = _
           New SqlParameter("@LineTotal", SqlDbType.Decimal)
        parameter.Value = 1.5
        command.Parameters.Add(parameter)

        ' Open the connection and load the data.
        connection.Open()
        Dim reader As SqlDataReader = _
           command.ExecuteReader(CommandBehavior.CloseConnection)
        table.Load(reader)

        ' Close the SqlDataReader
        reader.Close()
    End Using

    ' Display the SqlType of each column.
    Dim column As DataColumn
    Console.WriteLine("Data Types:")
    For Each column In table.Columns
        Console.WriteLine(" {0} -- {1}", _
        column.ColumnName, column.DataType.UnderlyingSystemType)
    Next column

    ' Display the value for each row.
    Dim row As DataRow
    Console.WriteLine("Values:")
    For Each row In table.Rows
        Console.Write(" {0}, ", row("SalesOrderID"))
        Console.Write(" {0}, ", row("UnitPrice"))
        Console.Write(" {0}, ", row("LineTotal"))
        Console.Write(" {0} ", row("ModifiedDate"))
        Console.WriteLine()
    Next row
End Sub

Vea tambiénSee also