SQL Server GUID sometimes valid and sometimes not - sql-server

Question

I'm having a problem with a GUID which I've narrowed down to what looks like a problem with the LIKE operator.
When the following is run on my server
DECLARE #Problem NVARCHAR(1000) = N'58C21BC6-081B-4E57-BFE1-5B11AAC662F1';
DECLARE #GuidPattern NVARCHAR(1000) =
REPLICATE('[0-9A-Fa-f]', 8)
+ '-'
+ REPLICATE('[0-9A-Fa-f]', 4)
+ '-'
+ REPLICATE('[0-9A-Fa-f]', 4)
+ '-'
+ REPLICATE('[0-9A-Fa-f]', 4)
+ '-'
+ REPLICATE('[0-9A-Fa-f]', 12);
SELECT
CASE
WHEN #Problem LIKE #GuidPattern THEN 1
ELSE 0
END AS [FollowsPattern];
the answer is 0, but when I run the exact same code on my local machine the answer is 1.
It looks pretty obvious to me that the string is in fact a valid GUID, so the answer should be 1 in both cases. All the other ways I know about to confirm that the GUID is valid also succeed, both locally and on the server:
SELECT
CASE
WHEN CAST(#Problem AS UNIQUEIDENTIFIER) = #Problem THEN 1
ELSE 0
END AS [IsGuid1]; -- 1
SELECT
CASE
WHEN CONVERT(UNIQUEIDENTIFIER, #Problem) = #Problem THEN 1
ELSE 0
END AS [IsGuid2]; -- 1
SELECT
CASE
WHEN TRY_CONVERT(UNIQUEIDENTIFIER, #Problem) IS NOT NULL THEN 1
ELSE 0
END AS [IsGuid3]; -- 1
The server version is
Microsoft SQL Server 2016 (RTM) - 13.0.1601.5 (X64)
Apr 29 2016 23:23:58
Copyright (c) Microsoft Corporation
Enterprise Edition: Core-based Licensing (64-bit) on Windows Server 2012 R2 Standard 6.3 <X64> (Build 9600: ) (Hypervisor)
and my local installation version is
Microsoft SQL Server 2014 - 12.0.2000.8 (X64)
Feb 20 2014 20:04:26
Copyright (c) Microsoft Corporation
Express Edition (64-bit) on Windows NT 6.1 <X64> (Build 7601: Service Pack 1)
The default collation is the not the same (SQL_Latin1_General_CP1_CI_AS locally and Danish_Norwegian_CI_AS on the server), but I don't think that should matter since I'm dealing with Unicode anyway. Adding an extra COLLATE clause on either machine with the other's collation makes no difference. Update: Not true, the collation is the source of the problem. I only tested different collations in the variable declaration, not in the comparison itself.

Answer 1

I suppose the problem is COLLATION.
Have a look at: http://rextester.com/IRQEFU33639
If you use default collation:
SELECT
CASE
WHEN #Problem LIKE #GuidPattern THEN 1
ELSE 0
END AS [FollowsPattern];
The result = 1
Instead, if you forces Danish_Norwegian_CI_AS collation:
SELECT
CASE
WHEN #Problem collate Danish_Norwegian_CI_AS LIKE #GuidPattern THEN 1
ELSE 0
END AS [FollowsPattern];
It returns 0.
I'd suggest to force the collation to SQL_Latin1_General_CP1_CI_AS or other collation that works well.
SELECT
CASE
WHEN #Problem COLLATE SQL_Latin1_General_CP1_CI_AS LIKE #GuidPattern THEN 1
ELSE 0
END AS [FollowsPattern];
And just to make it easy maybe using an INLINE User Defined Function.

Answer 2

Force to a standard collation
SELECT
CASE
WHEN #Problem COLLATE Latin1_General_CI_AS LIKE #GuidPattern COLLATE Latin1_General_CI_AS THEN 1
ELSE 0
END AS [FollowsPattern];
The reason is how "a" is matched in Danish_Norwegian_CI_AS collation.
See SQL 'Like' operator and 'aa' for more where I demonstrated it with Danish_Norwegian_CI_AS