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Editorial Team
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Asked: 2026-06-03T06:12:36+00:00

I was wondering if someone can explain this behaviour? DECLARE @RandomParam1 NVARCHAR DECLARE @RandomParam2

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I was wondering if someone can explain this behaviour?

DECLARE @RandomParam1 NVARCHAR
DECLARE @RandomParam2 NVARCHAR
DECLARE @RandomParam3 NVARCHAR
SET @RandomParam1 = '0HelloWorld'
SET @RandomParam2 = '9HelloWorld'
SET @RandomParam3 = '15HelloWorld'

select 1 where '0' = @RandomParam1  -- true
select 1 where '0' = '0HelloWorld'  -- false

select 1 where '9' = @RandomParam2  -- true
select 1 where '15' = @RandomParam3 -- false

Why does a string comparison with parameters yield a different result than without parameters? And why does it claim that ‘0’ = ‘0whatever’?

I get that it may be that the parameter tries to compare it as numbers, but then the last example should be true aswell.

Any ideas?

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1 Answer

  1. Editorial Team

    The default length for NVARCHAR is 1. Your three parameters effectively all contain just one single character.

    If you change your declarations to 

    DECLARE @RandomParam1 NVARCHAR(32)
DECLARE @RandomParam2 NVARCHAR(32)
DECLARE @RandomParam3 NVARCHAR(32)

    you will get the behavior you were expecting.

    nchar and nvarchar

    When n is not specified in a data definition or variable declaration
    statement, the default length is 1.

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