Nvarchar trailling spaces

Question

Hello together,
I have made a table:
/****** Object: Table [dbo].[testTable] Script Date: 30.04.2015 12:22:11 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[testTable](
[Id] [int] NOT NULL,
[text] [nvarchar](255) NOT NULL
) ON [PRIMARY]
GO
now i have inserted two rows
one row Id = 1 and text='hallo'
second row Id = 2 and text='hallo '     (trailling space)
after this i have made an update:
update testTable set id=4 where Text=N'hallo'
after this i get the message: (2 row(s) affected)
and both rows hat the Id=4
I'm not happy with this behavior.
What can I do?
thanks for your reply

Answer 1

Reason: This is because SQL Server ignores trailing spaces while making comparison through "=". Ex. "Text" is similar to "Text  " in SQL in comparison.
To avoid that use DATALENGTH to calculate the actual length of the column.. not LEN()
Sample
CREATE TABLE [dbo].[testTable](
[Id] [int] NOT NULL,
[text] [nvarchar](255) NOT NULL
) ON [PRIMARY]
Insert into [dbo].[testTable] VALUES
(1,'hallo'),
(2,'hallo ')
DECLARE @SearchText nvarchar(255) = 'hallo'
update testTable set id=4 where Text=@SearchText
AND DATALENGTH(text) = DATALENGTH(@SearchText);
SELECT *, ASCII(text),DATALENGTH(text) FROM [dbo].[testTable]
SQL Fiddler code
Hope this will help
Edit:
I was bit too late, please consider Olaf
Helper & Erland
Sommarskog answers. +1 for quick response. 
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