What are single-byte character string data types supported in SQL Server Transact-SQL?

Single-byte character string data types are used to hold single-byte character strings.

There are 3 single-byte character string data types supported in SQL Server Transact-SQL:

1. CHAR (or CHARACTER) - Used to hold single-byte character strings of a fixed length specified in the format of CHAR(n), where n defines the string length as number of characters. The maximum length of CHAR is 8,000 single-byte characters.

The storage size of CHAR(n) is fixed to n bytes, regardless of the length of the string value.

2. VARCHAR (or CHAR VARYING, or CHARACTER VARYING) - Use to hold ASCII character strings of variable lengths specified in the format of VARCHAR(n), where n defines the string length as number of characters. The maximum length of VARCHAR is 8,000 single-byte characters.

The storage size of VARCHAR(n) is flexible up to n+2 bytes, depending on the length of the string value. The extra 2 bytes are used to store the length of the string value.

3. TEXT (or VARCHAR(MAX)) - Use to hold single-byte character strings of very large lengths. TEXT uses the CLOB (Character Large OBject) technology to store string values. TEXT can store string values of variable lengths up to 2^31-1 (2,147,483,647) characters.

Here are some good examples of single-byte character string values:

PRINT 'Hello!    '; -- CHAR(10)
PRINT 'Hello!'; -- VARCHAR(10)

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