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Concatenation with NULL values
From Wiki
How do you concatenate with NULL values? If you concatenate a two values and one of them is NULL then the result will be NULL
Run this to see what I mean
- DECLARE @var1 VARCHAR(50)
- DECLARE @var2 VARCHAR(50)
- SELECT @var1 ='Test'
- SELECT @var1 + @var2
That returned NULL
You can use ISNULL or COALESCE
- DECLARE @var1 VARCHAR(50)
- DECLARE @var2 VARCHAR(50)
- SELECT @var1 ='Test'
- SELECT @var1 + ISNULL(@var2,'')
- SELECT @var1 + COALESCE(@var2,'')
You can also the CONCAT_NULL_YIELDS_NULL setting but I would not mess with it, I only show it because it is possible to use it.
- DECLARE @var1 VARCHAR(50)
- DECLARE @var2 VARCHAR(50)
- SELECT @var1 ='Test'
- SET CONCAT_NULL_YIELDS_NULL OFF
- SELECT @var1 + @var2
- SET CONCAT_NULL_YIELDS_NULL ON
Contributed by: --SQLDenis 16:34, 30 May 2008 (GMT)
Part of SQL Server Programming Hacks
Section NULLS
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