What Is String Data Type in SQL Server?


Larry Thompson

The string data type in SQL Server is used to store and manipulate text data. It is one of the most commonly used data types in any database management system. In this article, we will explore the various aspects of the string data type, its properties, and how it can be effectively utilized in SQL Server.

Characteristics of String Data Type

1. Variable Length:

A string can have a variable length, which means it can store a varying number of characters. The maximum length of a string depends on the specific version and edition of SQL Server you are using.

2. Unicode Support:

SQL Server supports both non-Unicode (ANSI) and Unicode characters. Non-Unicode strings are limited to a specific character set, such as ASCII or ISO-8859-1, while Unicode strings can represent characters from various languages and scripts.

3. Collation:

Collation defines the rules for comparing and sorting strings in SQL Server.

It determines how string comparisons are performed, taking into account factors like case-sensitivity, accent sensitivity, and character width. SQL Server provides a wide range of collations to suit different language requirements.

Data Types for Storing Strings

In SQL Server, there are two main data types for storing strings:


  • Syntax: VARCHAR(max_length)
  • VARCHAR is used to store variable-length non-Unicode character data.
  • The max_length parameter specifies the maximum number of characters that can be stored in the column.


  • Syntax: NVARCHAR(max_length)
  • NVARCHAR is used to store variable-length Unicode character data.

Both VARCHAR and NVARCHAR can store strings of varying lengths, but NVARCHAR can handle a wider range of characters due to its Unicode support.

Working with String Data Type

SQL Server provides a set of built-in functions and operators to perform various operations on string data. Some commonly used functions include:

  • LEN: Returns the length (number of characters) of a string.
  • UPPER: Converts all characters in a string to uppercase.
  • LOWER: Converts all characters in a string to lowercase.
  • SUBSTRING: Extracts a substring from within a string based on the specified starting position and length.

In addition to these functions, SQL Server also supports concatenation (combining two or more strings), pattern matching using wildcard characters, and various other string manipulation operations.


The string data type in SQL Server is essential for storing and manipulating text data. Whether you need to store names, addresses, or any other textual information, understanding the characteristics and proper usage of the string data type is crucial. By utilizing the appropriate data type (VARCHAR or NVARCHAR) and leveraging the available functions, you can efficiently work with strings in SQL Server and build robust database applications.

To summarize, the string data type provides flexibility, Unicode support, and collation options for efficient handling of text data in SQL Server.

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