SQL Stored Procedure Optional Parameter - sql

Question

I am trying to create a Stored Procedure as follows -
CREATE PROCEDURE [dbo].[Chargeable_Time] #DateFrom DATE,
#DateTo DATE,
#Allocated INT = NULL
AS
SELECT t.CaseID,
c.DisplayNo,
c.CaseName,
c.[Category],
t.[Date],
t.FeeEarner,
u.Username,
t.ChargeCode,
t.[Hours],
t.Fees,
t.GroupID,
( CASE
WHEN t.GroupID IS NOT NULL THEN 1
WHEN t.GroupID IS NULL THEN 0
END ) AS Allocated
FROM Timesheet AS t
LEFT JOIN [User] AS u
ON t.FeeEarner = u.ID
LEFT JOIN [Case] AS c
ON t.CaseID = c.ID
WHERE t.Active = 'True'
AND t.CaseID IS NOT NULL
AND t.Rate > 0
AND t.[Date] >= #DateFrom
AND t.[Date] <= #DateTo
AND Allocated = #Allocated
However I have two problems -
The Allocated field is not recognised as it is created by the procedure rather than being a field in the underlying tables, and
I want to be able to return all data if the Allocated field is left NULL. As it currently stands anyone calling the procedure can enter a 0 or 1 to filter the results, but I want them to also be able to leave the parameter blank and get the full set without the filter. I am not sure how to do this.
Any help would be greatly appreciated.

Answer 1

You can change the last part of the code as follows
Create PROCEDURE [dbo].[Chargeable_Time]
#DateFrom DATE,
#DateTo DATE,
#Allocated INT = NULL
AS
Begin
SELECT t.CaseID,
c.DisplayNo,
c.CaseName,
c.[Category],
t.[Date],
t.FeeEarner,
u.Username,
t.ChargeCode,
t.[Hours],
t.Fees,
t.GroupID,
( CASE
WHEN t.GroupID IS NOT NULL THEN 1
WHEN t.GroupID IS NULL THEN 0
END ) AS Allocated
FROM Timesheet AS t
LEFT JOIN [User] AS u
ON t.FeeEarner = u.ID
LEFT JOIN [Case] AS c
ON t.CaseID = c.ID
WHERE t.Active = 'True'
AND t.CaseID IS NOT NULL
AND t.Rate > 0
AND t.[Date] >= #DateFrom
AND t.[Date] <= #DateTo
AND (( CASE
WHEN t.GroupID IS NOT NULL THEN 1
WHEN t.GroupID IS NULL THEN 0
END ) = #Allocated OR #Allocated is null )
END
GO

Answer 2

This should do the trick. However this can be a bad solution when there is lot's of data. You should test that. Some reading about this kind of solution:
https://www.sqlskills.com/blogs/kimberly/high-performance-procedures/
CREATE PROCEDURE [dbo].[Chargeable_Time]
#DateFrom DATE,
#DateTo DATE,
#Allocated INT = NULL
AS
SELECT
t.CaseID,
c.DisplayNo,
c.CaseName,
c.[Category],
t.[Date],
t.FeeEarner,
u.Username,
t.ChargeCode,
t.[Hours],
t.Fees,
t.GroupID,
(CASE WHEN t.GroupID IS NOT NULL THEN 1
WHEN t.GroupID IS NULL THEN 0
END
) AS Allocated
FROM Timesheet AS t
LEFT JOIN [User] AS u ON t.FeeEarner = u.ID
LEFT JOIN [Case] AS c ON t.CaseID = c.ID
WHERE t.Active = 'True'
AND t.CaseID IS NOT NULL
AND t.Rate > 0
AND t.[Date] >= #DateFrom
AND t.[Date] <= #DateTo
AND (CASE WHEN t.GroupID IS NOT NULL THEN 1
WHEN t.GroupID IS NULL THEN 0
END
) = #Allocated
OR #Allocated IS NULL;

Answer 3

You can simplify your code by using CROSS APPLY:
CREATE PROCEDURE [dbo].[Chargeable_Time]
#DateFrom DATE,
#DateTo DATE,
#Allocated INT = NULL
AS
Begin
SELECT t.CaseID,
c.DisplayNo,
c.CaseName,
c.[Category],
t.[Date],
t.FeeEarner,
u.Username,
t.ChargeCode,
t.[Hours],
t.Fees,
t.GroupID,
a.Allocated
FROM Timesheet AS t
CROSS APPLY (VALUES (CASE WHEN t.GroupID IS NOT NULL THEN 1
WHEN t.GroupID IS NULL THEN 0
END )) As a(Allocated)
LEFT JOIN [User] AS u
ON t.FeeEarner = u.ID
LEFT JOIN [Case] AS c
ON t.CaseID = c.ID
WHERE t.Active = 'True'
AND t.CaseID IS NOT NULL
AND t.Rate > 0
AND t.[Date] >= #DateFrom
AND t.[Date] <= #DateTo
AND (#Allocated IS NULL OR a.Allocated = #Allocated)
END
GO