The nvarchar data type in SQL Server is a variable-length Unicode character data type that is designed to store character data in a multi-byte character set, such as UTF-16. The variable-length must be a value from 1 through 4,000. It is one of the most commonly used data types for handling text data in SQL Server databases. The "n" in nvarchar stands for "national," indicating that it is used for storing national language character data.

Nvarchar syntax:

nvarchar [ ( n ) ]
nvarchar [ ( max ) ]

Here are some key points to understand about the nvarchar data type in SQL Server:

Unicode Support: nvarchar is used for storing Unicode character data, which allows it to represent a wide range of characters, including those from various languages, special symbols, and emojis. This makes it suitable for applications that need to support multiple languages and character sets.

Variable-Length: The "var" in nvarchar stands for variable, which means that the length of the data can vary from one row to another. This is in contrast to fixed-length character data types like char, which always consume the same amount of storage regardless of the actual data length.

Storage Size: The storage size of nvarchar is typically twice the number of characters entered plus two bytes to store the length of the data. This is because Unicode characters are represented in UTF-16, which uses two bytes per character. The extra two bytes are used to store the length of the data.

Use Cases: nvarchar is commonly used for storing text data in database columns, such as names, descriptions, and comments, where you need to support a wide range of characters. It is especially important in multilingual applications where data needs to be stored and retrieved in different languages.

Collation: nvarchar data is affected by the collation settings of the database or specific columns. Collation determines how string comparison and sorting operations are performed. It's important to choose an appropriate collation to ensure accurate string comparisons and sorting based on the language and region of your data.

Performance Considerations: Because nvarchar columns can store variable-length data, they may have a slight performance overhead compared to fixed-length data types like char. However, this is often outweighed by the benefits of Unicode support and flexibility in handling multilingual data.

Nvarchar example:

USE model;
GO
CREATE TABLE nvarcharTable ( a nvarchar(25) );
GO
INSERT INTO nvarcharTable VALUES ('This is an example');
GO
SELECT a FROM nvarcharTable;
GO

Results: This is an example

The nvarchar data type in SQL Server is a versatile option for storing Unicode character data, making it a popular choice for applications that require support for different languages and character sets. It offers the flexibility of variable-length storage while ensuring that your database can handle a wide range of characters and symbols, making it an essential part of many database designs.