SQL Server T-SQL N prefix on string literal

Question

It's maybe a noob question but I found some T-SQL query example to verify database size with SELECT and WHERE clause here

Here is the code:

SELECT name, size, size*1.0/128 AS [Size in MBs] 
FROM sys.master_files
WHERE name = N'mytest';

My question is what does the N prefix mean in the WHERE name = N'keyword' clause?

I always use WHERE name = 'keyword' before, and I don't find the differences (you can try it by yourself).

I've googled that but I don't know the keyword I supposed to search

score 5 · Accepted Answer · edited May 23 '17 at 12:05

5

It's declaring the string as nvarchar data type (Unicode), rather than varchar (8-bit encoding, including ASCII).

FYI, this is a duplicate of the question: What is the meaning of the prefix N in T-SQL statements?

edited May 23 '17 at 12:05

Community

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answered Oct 11 '13 at 18:56

Doug_Ivison

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This is not quite correct. Varchar is not ASCII. Varchar is an 8 bit encoding. It can store ASCII, or it can store any other 8 bit code page for that matter. – Stainy Oct 11 '13 at 20:10

score 2 · Answer 2 · answered Oct 11 '13 at 18:53

From the docs:-

You may have seen Transact-SQL code that passes strings around using an N prefix. This denotes that the subsequent string is in Unicode (the N actually stands for National language character set). Which means that you are passing an NCHAR, NVARCHAR or NTEXT value, as opposed to CHAR, VARCHAR or TEXT.

score 2 · Answer 3 · answered Oct 11 '13 at 18:53

2

N means there can be some unicode characters in the given string.

answered Oct 11 '13 at 18:53

M.Ali

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score 1 · Answer 4 · answered Oct 11 '13 at 18:54

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It means unicode. See http://msdn.microsoft.com/en-us/library/bb399176.aspx To declare a character string literal as Unicode, prefix the literal with an uppercase "N"

answered Oct 11 '13 at 18:54

Mike Stockdale

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SQL Server T-SQL N prefix on string literal

4 Answers4

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