What is mean N'123456'?

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What is mean N'123456'?

adonetok

SSCrazy Eights

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March 26, 2014 at 6:39 am

#287034

What is mean N'123456 in code below?
Select * from order where orderID=N'123456'

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Eirikur Eiriksson SSC Guru Points: 182920 More actions · Answer 1

The N denotes the N(VAR)CHAR type, without it the N it would be (VAR)Char.

😎

Jeff Moden SSC Guru Points: 1004435 More actions · Answer 2

It also means that unless the OrderID column is NVARCHAR, the code isn't SARGable (can't do an INDEX SEEK) and will cause a table scan to do an implicit conversion of all OrderIDs in the table to NVARCHAR because of the high order that NVARCHAR has for data precedence. This is very typical of ORM code and the database normally gets the blame instead of the ORM.

--Jeff Moden

RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

Change is inevitable... Change for the better is not.

Helpful Links:
How to post code problems
How to Post Performance Problems
Create a Tally Function (fnTally)

adonetok SSCrazy Eights Points: 8395 More actions · Answer 3

Some users uploaded Access tables to SQL are always NVARCHAR type.

I found that nvarchar cause performace problem. Is it true?

Jeff Moden SSC Guru Points: 1004435 More actions · Answer 4

adonetok (3/26/2014)
Some users uploaded Access tables to SQL are always NVARCHAR type.
I found that nvarchar cause performace problem. Is it true?

I don't know why anyone that knew anything about table structure would store what is typically a "digits only" column as NVARCHAR or even VARCHAR. It not only makes for performance problems but causes "row bloat" (a performance, storage, backup, restore, and index problem to name just a few). If real numeric sorts are important, storing such "digit only" data really puts the screws to performance there. The users have made a terrible mistake by doing this themselves instead of working with the DBA on this.

As a side bar, this is why I don't allow users to have anything but read privs (sometimes, write but never DDL privs) in production. They just don't know what they don't know.

--Jeff Moden

RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

Change is inevitable... Change for the better is not.

Helpful Links:
How to post code problems
How to Post Performance Problems
Create a Tally Function (fnTally)

Umer Akram SSC-Insane Points: 22209 More actions · Answer 5

They just don't know what they don't know.

Thats a million dollar quote, Jeff

Bravooo !!!! :hehe:

Koen Verbeeck SSC Guru Points: 259125 More actions · Answer 6

twin.devil (3/26/2014)
They just don't know what they don't know.
Thats a million dollar quote, Jeff
Bravooo !!!! :hehe:

You can only achieve wisdom if you know what you don't know. 😉

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