SQL Server Character Data Types

Overview of SQL Server Character Data Types

SQL Server provides four primary character data types: char, varchar, nchar, and nvarchar.

These types differ in length behavior and Unicode support.

• char: Fixed-length, non-Unicode character data.
• varchar: Variable-length, non-Unicode character data.
• nchar: Fixed-length, Unicode character data.
• nvarchar: Variable-length, Unicode character data.

Fixed-Length vs Variable-Length

Fixed-length types always allocate the specified number of characters, padding with spaces if necessary.

Variable-length types allocate storage based on the actual length of the data, up to the defined maximum.

• Use fixed-length types when data length is consistent.
• Use variable-length types when data length varies significantly.

Unicode Support in SQL Server

Unicode data types support multiple languages and special characters by using two bytes per character.

Non-Unicode types use one byte per character but cannot store international characters reliably.

• Use nchar and nvarchar for multilingual applications.
• Use char and varchar for English or single-byte character sets to save space.

Examples of Character Data Types

Here are examples demonstrating how to declare columns with different character data types.