VARCHAR Vs NVARCHAR

	Varchar[(n)]	NVarchar[(n)]
Basic Definition	Non-Unicode Variable Length character data type. Example: DECLARE @FirstName ASVARCHAR(50) =‘BASAVARAJ’ SELECT @FirstName	UNicode Variable Length character data type. It can store both non-Unicode and Unicode (i.e. Japanese, Korean etc) characters. Example: DECLARE @FirstName ASNVARCHAR(50)= ‘BASAVARAJ’ SELECT @FirstName
No. of Bytes required for each character	It takes 1 byte per character Example: DECLARE @FirstName ASVARCHAR(50) = ‘BASAVARAJ’ SELECT @FirstName AS FirstName, DATALENGTH(@FirstName) AS  Length Result: FirstName Length BASAVARAJ 9	It takes 2 bytes per Unicode/Non-Unicode character. Example: DECLARE @FirstName ASNVARCHAR(50)= ‘BASAVARAJ’ SELECT @FirstName AS FirstName, DATALENGTH(@FirstName) AS Length Result: FirstName Length BASAVARAJ 18
Optional Parameter nrange	Optional Parameter n value can be from 1 to 8000.Can store maximum 8000 Non-Unicode characters.	Optional Parameter n value can be from 1 to 4000.Can store maximum 4000 Unicode/Non-Unicode characters
If Optional Parameter nis not specified in the variable declaration or column definition	If Optional parameter value n is not specified in the variable declaration or column definition then it is considered as 1. Example: DECLARE @firstName VARCHAR =‘BASAVARAJ’ SELECT @firstName FirstName,DATALENGTH(@firstName) Length Result: FirstName Length B 1	If Optional parameter value n is not specified in the variable declaration or column definition then it is considered as 1. Example: DECLARE @firstName NVARCHAR =‘BASAVARAJ’ SELECT @firstName FirstName,DATALENGTH(@firstName) Length Result: FirstName Length B 2
If Optional Parameter nis not specified in while using CAST/ CONVERT functions	When this optional parameter n is not specified while using the CAST/CONVERT functions, then it is considered as 30.Example: DECLARE @firstName VARCHAR(35)= ‘BASAVARAJ PRABHU BIRADAR INDIA ASIA’ SELECT CAST(@firstName ASVARCHAR) FirstName, DATALENGTH(CAST(@firstName ASVARCHAR)) Length Result: FirstName Length BASAVARAJ PRABHU BIRADAR INDIA 30	When this optional parameter n is not specified while using the CAST CONVERT functions, then it is considered as 30.Example: DECLARE @firstName NVARCHAR(35) = ‘BASAVARAJ PRABHU BIRADAR INDIA ASIA’ SELECT CAST(@firstName ASNVARCHAR) FirstName, DATALENGTH(CAST(@firstName ASNVARCHAR)) Length Result: FirstName Length BASAVARAJ PRABHU BIRADAR INDIA 60
Which one to use?	If we know that data to be stored in the column or variable doesn’t have any Unicode characters.	If we know that the data to be stored in the column or variable can have Unicode characters.
Storage Size	Takes no. of bytes equal to the no. of Characters entered plus two bytes extra for defining offset.	Takes no. of bytes equal to twice the no. of Characters entered plus two bytes extra for defining offset.