SQL Server - Masalah meneruskan variabel ke prosedur tersimpan

Anda tidak mendeklarasikan parameter, tetapi variabel lokal. Untuk mendeklarasikannya seperti yang Anda inginkan:

CREATE PROCEDURE pOrders (@enteredClientID varchar(20))
AS
    DECLARE @Results table (ClientID varchar(20), Num_orders int);

    SET NOCOUNT ON;

    -- Get all the order from the client
    INSERT INTO @Results
    SELECT ClientID, sum(Num_orders)
    FROM Orders O
    WHERE O.ClientID = @enteredClientID
    GROUP BY O.ClientID);

    -- Insert the orders into the results table --
    SELECT *
    FROM @Results;

GO;

Sebut saja:

exec pOrders @enteredClientID = 'ABC123456789'

atau cukup

exec pOrders 'ABC123456789'