Default to a value when a sub-query statement fails? - sql

Question

I have the following query:
INSERT INTO dbo.ResourceOrderCustomersOrders
( OrderId ,
Type ,
CustomerId ,
ResourceId ,
Quantity ,
Created ,
CreatedBy
)
VALUES ( ( SELECT MAX(OrderId) + 1
FROM dbo.ResourceOrderCustomersOrders
) , -- OrderId - int
'PENDING' , -- Type - varchar(50)
( SELECT MAX(CustomerId)
FROM dbo.ResourceOrderCustomers
WHERE UPPER(FirstName) = UPPER(#Firstname)
AND UPPER(Surname) = UPPER(#Surname)
AND UPPER(Email) = UPPER(#Email)
) , -- CustomerId - int
( SELECT MAX(ResourceId)
FROM dbo.ResourceOrderFormContent
WHERE DisplayTitle = #ResourceName
) , -- ResourceId - int
#ResourceQuantity ,
GETDATE() , -- Created - datetime
'WebsiteForm' -- CreatedBy - varchar(20)
);
In cases where a subquery fails I'd like to default to a value of my choosing (to hold unspecified records).
For example, were the following to fail to retrieve a result because a record doesn't exist:
SELECT MAX(ResourceId)
FROM dbo.ResourceOrderFormContent
WHERE DisplayTitle = #ResourceName
Then I would want to return the number '999' (unspecified record). What would be the best way to approach this?
I've tried to use try / catch but I'm being told this is invalid syntax. Here is my attempt:
INSERT INTO dbo.ResourceOrderCustomersOrders
( OrderId ,
Type ,
CustomerId ,
ResourceId ,
Quantity ,
Created ,
CreatedBy
)
VALUES ( ( SELECT MAX(OrderId) + 1
FROM dbo.ResourceOrderCustomersOrders
) , -- OrderId - int
'PENDING' , -- Type - varchar(50)
( SELECT MAX(CustomerId)
FROM dbo.ResourceOrderCustomers
WHERE UPPER(FirstName) = UPPER(#Firstname)
AND UPPER(Surname) = UPPER(#Surname)
AND UPPER(Email) = UPPER(#Email)
) , -- CustomerId - int
( BEGIN TRY
SELECT MAX(ResourceId)
FROM dbo.ResourceOrderFormContent
WHERE DisplayTitle = #ResourceName
END TRY
BEGIN CATCH
SELECT 999
END CATCH
) , -- ResourceId - int
#ResourceQuantity ,
GETDATE() , -- Created - datetime
'WebsiteForm' -- CreatedBy - varchar(20)
);

Answer 1

Max will always return NULL if no rows found. So You can use ISNULL.
SELECT ISNULL(MAX(ResourceId), 999)
FROM dbo.ResourceOrderFormContent
WHERE DisplayTitle = #ResourceName