SQL Server NCHAR Data Type, NCHAR vs. CHAR

Summary: in this tutorial, you will learn how to use the SQL Server NCHAR data type to store fixed-length, Unicode character string data.

To store fixed-length, Unicode character string data in the database, you use the SQL Server NCHAR data type:

NCHAR(n)
Code language: SQL (Structured Query Language) (sql)

In this syntax, n specifies the string length that ranges from 1 to 4,000. The storage size of a NCHAR value is two times n bytes.

The ISO synonyms for NCHAR are NATIONAL CHAR and NATIONAL CHARACTER, therefore, you can use them interchangeably.

Similar to the CHAR data type, you use the NCHAR for storing fixed-length character string only. If the lengths of data values are variable, you should consider using VARCHAR or NVARCHAR data type.

CHAR vs. NCHAR

The following are the major differences between CHAR and NCHAR data types

CHAR	NCHAR
Store only non-Unicode characters.	Store Unicode characters in the form of UNICODE UCS-2 characters.
Need 1 byte to store a character	Need 2 bytes to store a character.
The storage size equals the size specified in the column definition or variable declaration.	The storage size equals double the size specified in the column definition or variable declaration.
Store up to 8000 characters.	Store up to 4000 characters.

SQL Server `NCHAR` example

The following statement creates a new table with one NCHAR column:

CREATE TABLE test.sql_server_nchar (
    val NCHAR(1) NOT NULL
);
Code language: SQL (Structured Query Language) (sql)

The following INSERT statement inserts the character a (あ) in Japanese into the NCHAR column:

INSERT INTO test.sql_server_nchar (val)
VALUES
    (N'あ');
Code language: SQL (Structured Query Language) (sql)

Notice that you must prefix the Unicode character string constants with the letter N. Otherwise, SQL Server will convert the string to the default code page of the database which may not recognize some certain Unicode characters.

If you insert a character string whose length is greater than the length specified in the column definition, SQL Server issues an error and terminates the statement.

For example, the following statement attempts to insert a string with two characters into the val column of test.sql_server_nchar table:

INSERT INTO test.sql_server_nchar (val)
VALUES
    (N'いえ'); 
Code language: SQL (Structured Query Language) (sql)

SQL Server issued the following error message:

String or binary data would be truncated.
The statement has been terminated. 
Code language: SQL (Structured Query Language) (sql)

To find the number of characters and the number of bytes of the values the val column, you use the LEN and DATALENGTH functions as follows:

SELECT
    val,
    len(val) length,
    DATALENGTH(val) data_length
FROM
    test.sql_server_nchar;
Code language: SQL (Structured Query Language) (sql)

In this tutorial, you have learned how to use the SQL Server NCHAR data type to store fixed-length, Unicode character strings in the database.

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CHAR vs. NCHAR

CHAR

NCHAR

SQL Server NCHAR example

SQL Server `NCHAR` example