The primary difference between NVARCHAR and VARCHAR lies in their ability to store data in different character encodings and their memory requirements. Here’s a detailed comparison:
| Aspect | NVARCHAR | VARCHAR |
|---|---|---|
| Encoding | Stores data in Unicode format (UTF-16), supporting multiple languages and special characters. | Stores data in non-Unicode format, limited to a specific code page (e.g., ASCII). |
| Character Support | Supports international characters (e.g., Chinese, Arabic, emojis). | Limited to English-like characters (based on the collation and code page). |
| Storage Size | Uses 2 bytes per character for Unicode storage. | Uses 1 byte per character (for standard ASCII characters). |
| Use Case | Ideal for applications with multilingual data or special characters. | Ideal for single-language applications with ASCII-based characters. |
| Performance | Slightly slower than VARCHAR due to additional memory usage and processing for Unicode. | Slightly faster because it uses less memory for ASCII characters. |
| Max Length | Supports up to 4,000 characters (for older versions) or 2 GB of storage. | Supports up to 8,000 characters (for older versions) or 2 GB of storage. |
Key Points to Remember:
- Unicode Advantage:
- If you need to store text in multiple languages (e.g., Chinese, Japanese, Hindi), always use
NVARCHAR. - Unicode ensures that characters from different scripts are handled correctly.
- If you need to store text in multiple languages (e.g., Chinese, Japanese, Hindi), always use
- Performance Trade-off:
VARCHARis more efficient for storage and performance when dealing with only ASCII or a single language.- However, it lacks the ability to store international characters.
- Storage Size Example:
- For the string “hello”:
VARCHAR(10)will use 5 bytes.NVARCHAR(10)will use 10 bytes (2 bytes per character).
- For the string “hello”:
Recommendation:
- Use
NVARCHARif your application handles multilingual data or requires support for special characters. - Use
VARCHARif your application deals only with ASCII characters and prioritizes performance and reduced storage.