When working with SQL databases, you may come across two commonly used data types for storing textual data: VARCHAR and NVARCHAR. While they may seem similar, there are some important differences between the two. In this blog post, we will explore VARCHAR and NVARCHAR and discuss when and how to use them.

What are VARCHAR and NVARCHAR?

• VARCHAR (Variable Character) is a data type used to store non-Unicode character data. It can store alphanumeric characters and special symbols, but not multilingual data.

• NVARCHAR (National Variable Character) is a data type used to store Unicode character data. It can store not only alphanumeric characters and special symbols but also multilingual data, including characters from various languages and scripts.

Character Encoding

The primary difference between VARCHAR and NVARCHAR is the way they handle character encoding.

• VARCHAR uses a single-byte character encoding, such as ASCII or UTF-8. Each character is represented using one byte, which is suitable for storing characters from a single language.

• NVARCHAR uses a double-byte character encoding, such as UTF-16. Each character is represented using two bytes, which allows for the storage of multilingual data.

Storage Space

Since NVARCHAR uses double the storage space compared to VARCHAR, it is important to consider the potential impact on storage requirements.

For example, if you have a VARCHAR(100) column, it will occupy 100 bytes of storage space. However, an NVARCHAR(100) column will occupy 200 bytes of storage space.

Therefore, it is crucial to choose the appropriate data type based on the requirements of your application. If multilingual support is required or the application needs to handle data from different languages, NVARCHAR should be chosen.

Performance Considerations

While NVARCHAR allows for the storage of multilingual data, it can impact performance due to the increased storage requirements. Operations such as data retrieval, sorting, and indexing can be slower when working with NVARCHAR columns compared to VARCHAR columns.

If your application does not require multilingual support, it is recommended to use VARCHAR for improved performance. However, if you need to handle text in multiple languages, the performance difference may be negligible and the benefits of multilingual support outweigh the potential performance impact.

Key Takeaways

• VARCHAR is suitable for storing non-Unicode character data, while NVARCHAR is designed for storing Unicode character data, including multilingual text.

• VARCHAR uses a single-byte character encoding, whereas NVARCHAR uses a double-byte character encoding, which impacts storage requirements.

• Consider the storage space and performance implications when choosing between VARCHAR and NVARCHAR. Use VARCHAR for non-multilingual text data and NVARCHAR for Unicode/multilingual support.

In the end, choosing the right data type depends on the needs of your application.