Differences Between CHAR, VARCHAR, NCHAR, and NVARCHAR in SQL Server

Text storage in SQL Server isn’t one-size-fits-all. Understanding the differences between CHAR, VARCHAR, NCHAR, and NVARCHAR is crucial for efficient database design and correct handling of international characters. This guide breaks down how each data type works, when to use them, and common mistakes to avoid so you can optimize both performance and storage.

Data Type Differences

• CHAR – Fixed-length, non-Unicode. Best for consistent-size data (e.g., codes).
• VARCHAR – Variable-length, non-Unicode. Saves space for ASCII-only text.
• NCHAR – Fixed-length, Unicode. Each character = 2 bytes. Use for fixed-size multilingual text.
• NVARCHAR – Variable-length, Unicode. Recommended for most text fields, especially with multiple languages.

Common Mistakes

• Using fixed-length (CHAR/NCHAR) for variable text → wastes space.
• Using non-Unicode (CHAR/VARCHAR) for multilingual data → causes corruption.

Rules of Thumb

• Fixed length → CHAR / NCHAR.
• Variable length → VARCHAR / NVARCHAR.
• Need Unicode? → Prefer NVARCHAR.