What is the difference Between CHAR and NCHAR data types?

CHAR

• CHAR data type is used to store non-Unicode string data of fixed-length.
• Stores data at 1 byte per character.
• Supports up to 8000 characters.

Syntax
char(n)

n specify the string length that ranges from 1 to 8000. Default value for n is 1.

NCHAR

• NCHAR data type is used to store Unicode string data of fixed-length.
• It stores data at 2 byte per character.
• It supports up to 4000 characters.

Syntax
nchar(n)

n specify the string length that ranges from 1 to 4000. Default value for n is 1.

Lets demonstrate the difference between CHAR vs NCHAR

Data Storage Vs Length

• CHAR

In following T-SQL, declared a variable @str that is of datatype char of size 15.

DECLARE @Str CHAR(15)
SET @Str = 'Microsoft'
SELECT @Str AS Strtext, DATALENGTH(@Str) AS StrText_OccupiedLength ,
LEN(@Str) AS StrText_length

As char has fixed-length and takes 1 bytes per character to store the data so it takes 15 bytes to store value ‘microsoft’ , even though the length of value ‘microsoft’  is 9 .

So the data storage length of characters will be the fixed-length of variable @str* 1 bytes (15 *1) =15.

• NCHAR

In following T-SQL, declared a variable @str that is of datatype nchar of size 15.

DECLARE @Str NCHAR(15)
SET @Str = 'Microsoft'
SELECT @Str AS Strtext, DATALENGTH(@Str) AS StrText_OccupiedLength ,
LEN(@Str) AS StrText_length

As nchar has fixed-length and takes 2 bytes per character to store the data so it takes 30 bytes to store @str value ‘microsoft’ , even though the length of  value ‘microsoft’ is 9 .

So the data storage length of characters will be the fixed-length of variable @str * 2 bytes (15 *1) =30.

Using CHAR and NCHAR to store Unicode Data

• CHAR

Char can not store unicode data, here we try to store Hindi language text to @str variable of type char.

Note: Always make sure that you prefix Unicode string literals with an N prefix.

DECLARE @Str CHAR(15)
SET @Str = N'माइक्रोसॉफ्ट'
SELECT @Str AS Strtext, DATALENGTH(@Str) AS StrText_OccupiedLength ,
LEN(@Str) AS StrText_length

 

As you can see, it does not support unicode characters /multilingual data.

• NCHAR

NCHAR can store unicode data, again we try to store hindi language text to @str variable of type nchar.

Note: Always make sure that you prefix Unicode string literals with an N prefix.

DECLARE @Str NCHAR(15)
SET @Str = N'माइक्रोसॉफ्ट'
SELECT @Str AS Strtext, DATALENGTH(@Str) AS StrText_OccupiedLength ,
LEN(@Str) AS StrText_length

You can see, it returns the unicode data that can be seen in the first column of result set.

Also Read..

SQL Server VARCHAR VS NVARCHAR

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