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Difference between Sql Server Char and Varchar Data Type

What is difference between nvarchar and char?



CHAR Data Type is a Fixed Length Data Type. For example if you declare a variable/column of CHAR (10) data type, then it will always take 10 bytes irrespective of whether you are storing 1 character or 10 character in this variable or column. And in this example as we have declared this variable/column as CHAR (10), so we can store max 10 characters in this column.

VARCHAR is a variable length Data Type. For example if you declare a variable/column of VARCHAR (10) data type, it will take the no. of bytes equal to the number of characters stored in this column. So, in this variable/column if you are storing only one character then it will take only one byte and if we are storing 10 characters then it will take 10 bytes

DECLARE @Char Char(20) = 'MEHUL',
  @VarChar VarChar(20) = '  MEHUL'
 SELECT DATALENGTH(@Char) CharSpace,
  DATALENGTH(@VarChar) VarCharSpace
Result:



DECLARE @FirstName Char(20) = 'MEHUL',
  @LastName Char(20) = 'MAHERIYA'

SELECT  @FirstName + ' ' + @LastName AS Name,
 len(@FirstName + ' ' + @LastName) AS Length


 Go


 DECLARE @FirstName VarChar(20) = 'MEHUL',
 @LastName VarChar(20) = 'MAHERIYA'


SELECT  @FirstName + ' ' + @LastName AS Name,
 len(@FirstName + ' ' + @LastName) AS Length

So, it is clear from the above examples that during concatenation of CHAR data type variables, it includes space in-place of unused space in the result of concatenation.

Data Type
Length
Storage Size
Max Characters
Unicode
char
Fixed
Always n bytes
8,000
No; each character requires 1 byte
varchar
Variable
Actual length of entry in bytes
8,000
No; each character requires 1 byte
nchar
Fixed
Twice n bytes
4,000
Yes; each character requires 2 bytes
nvarchar
Variable
Twice actual length of entry in bytes
4,000
Yes; each character requires 2 bytes




Difference between Sql Server VARCHAR and NVARCHAR Data Type
Difference between Sql Server NCHAR and NVARCHAR Data Type

NCHAR data type:
1     Is a fixed length data type
2    Used to store Unicode characters (for example the languages Arabic,  German and so on)
       Occupies 2 bytes of space for each character

DECLARE @name NCHAR(10) 
SET @name = 'MEHUL' 
SELECT @name AS 'Name', DATALENGTH(@name) AS 'Datalength' , LEN(@name) AS 'Len'

NVARCHAR data type:
  • It is a variable-length data type
  • Used to store Unicode characters
  • Occupies 2 bytes of space for each character

DECLARE @name NVARCHAR(50) 
SET @name = 'MEHUL' 
SELECT @name AS 'Name', DATALENGTH(@name) AS 'Datalength' , LEN(@name) AS 'Len'


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