Редагувати

Поділитися через

How to: Use Stored Procedures that Take Parameters

  • Стаття

LINQ to SQL maps output parameters to reference parameters, and for value types declares the parameter as nullable.

For an example of how to use an input parameter in a query that returns a rowset, see How to: Return Rowsets.

Example 1

The following example takes a single input parameter (the customer ID) and returns an out parameter (the total sales for that customer).

CREATE PROCEDURE [dbo].[CustOrderTotal]
@CustomerID nchar(5),  
@TotalSales money OUTPUT  
AS  
SELECT @TotalSales = SUM(OD.UNITPRICE*(1-OD.DISCOUNT) * OD.QUANTITY)  
FROM ORDERS O, "ORDER DETAILS" OD  
where O.CUSTOMERID = @CustomerID AND O.ORDERID = OD.ORDERID  

[Function(Name="dbo.CustOrderTotal")]
[return: Parameter(DbType="Int")]
public int CustOrderTotal([Parameter(Name="CustomerID", DbType="NChar(5)")] string customerID, [Parameter(Name="TotalSales", DbType="Money")] ref System.Nullable<decimal> totalSales)
{
    IExecuteResult result = this.ExecuteMethodCall(this, ((MethodInfo)(MethodInfo.GetCurrentMethod())), customerID, totalSales);
    totalSales = ((System.Nullable<decimal>)(result.GetParameterValue(1)));
    return ((int)(result.ReturnValue));
}

<FunctionAttribute(Name:="dbo.CustOrderTotal")> _
 Public Function CustOrderTotal(<Parameter(Name:="CustomerID", DbType:="NChar(5)")> ByVal customerID As String, <Parameter(Name:="TotalSales", DbType:="Money")> ByRef totalSales As System.Nullable(Of Decimal)) As <Parameter(DbType:="Int")> Integer
    Dim result As IExecuteResult = Me.ExecuteMethodCall(Me, CType(MethodInfo.GetCurrentMethod, MethodInfo), customerID, totalSales)
    totalSales = CType(result.GetParameterValue(1), System.Nullable(Of Decimal))
    Return CType(result.ReturnValue, Integer)
End Function

Example 2

You would call this stored procedure as follows:

Northwnd db = new Northwnd(@"c:\northwnd.mdf");
decimal? totalSales = 0;
db.CustOrderTotal("alfki", ref totalSales);

Console.WriteLine(totalSales);

Dim db As New Northwnd("C:\...\northwnd.mdf")
Dim totalSales As Decimal? = 0
db.CustOrderTotal("alfki", totalSales)

Console.WriteLine(totalSales)

See also