What is the meaning of the prefix N in T-SQL statements and when should I use it?

I have seen prefix N in some insert T-SQL queries. Many people have used N before inserting the value in a table.

I searched, but I was not able to understand what is the purpose of including the N before inserting any strings into the table.

INSERT INTO Personnel.Employees
VALUES(N'29730', N'Philippe', N'Horsford', 20.05, 1),

What purpose does this ‘N’ prefix serve, and when should it be used?


Answer

It’s declaring the string as nvarchar data type, rather than varchar

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.

To quote from Microsoft:

Prefix Unicode character string constants with the letter N. Without
the N prefix, the string is converted to the default code page of the
database. This default code page may not recognize certain characters.


If you want to know the difference between these two data types, see this SO post:

What is the difference between varchar and nvarchar?

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