What is the purpose of putting an 'N' in front of function parameters in TSQL?

What is the purpose of putting an 'N' in front of function parameters in TSQL?

For example, what does the N mean in front of the function parameter in the follow开发者_StackOverflow中文版ing code:

object_id(N'dbo.MyTable')

It indicates a "nationalized" a.k.a. unicode string constant.

http://support.microsoft.com/kb/239530

When dealing with Unicode string constants in SQL Server you must precede all Unicode strings with a capital letter N, as documented in the SQL Server Books Online topic "Using Unicode Data".

http://msdn.microsoft.com/en-us/library/aa276823%28SQL.80%29.aspx

nchar and nvarchar

Character data types that are either fixed-length (nchar) or variable-length (nvarchar) Unicode data and use the UNICODE UCS-2 character set.

nchar(n)

Fixed-length Unicode character data of n characters. n must be a value from 1 through 4,000. Storage size is two times n bytes. The SQL-92 synonyms for nchar are national char and national character.

nvarchar(n)

Variable-length Unicode character data of n characters. n must be a value from 1 through 4,000. Storage size, in bytes, is two times the number of characters entered. The data entered can be 0 characters in length. The SQL-92 synonyms for nvarchar are national char varying and national character varying.