What Is the Data Type in SQL Server?


Scott Campbell

What Is the Data Type in SQL Server?

In SQL Server, data types play a crucial role in defining the type of data that can be stored in a table column or variable. Each data type has specific characteristics and storage requirements, allowing you to efficiently manage and manipulate data within your database.

Commonly Used Data Types

SQL Server provides a wide range of data types that cater to various requirements. Let’s explore some commonly used ones:

Numeric Data Types

INT: The INT data type is used to store whole numbers within the range of -2,147,483,648 to 2,147,483,647. It is commonly used for defining primary keys or auto-incrementing columns.

DECIMAL/NUMERIC: The DECIMAL or NUMERIC data type is suitable for storing fixed-point decimal numbers with user-defined precision and scale. This allows you to control the number of digits before and after the decimal point.

Date and Time Data Types

DATE: The DATE data type stores only date values without any time component. It has a range from January 1, 0001 to December 31, 9999.

DATETIME: The DATETIME data type represents both date and time values from January 1, 1753, through December 31, 9999. It provides precision down to milliseconds.

String Data Types

VARCHAR: The VARCHAR data type is used for variable-length character strings with a maximum length defined during column creation.

NVARCHAR: The NVARCHAR data type is similar to VARCHAR but is used for storing Unicode character strings. It is ideal for multilingual applications.

Binary Data Types

VARBINARY: The VARBINARY data type is used for variable-length binary data, such as images or files. It can store up to 2^31-1 bytes of data.

Other Data Types

BIT: The BIT data type represents a boolean value (0 or 1). It is commonly used for storing flags or indicators.

UNIQUEIDENTIFIER: The UNIQUEIDENTIFIER data type stores a globally unique identifier (GUID). It is often used for creating primary keys in distributed systems.

Data Type Considerations

When choosing a data type, it’s essential to consider factors such as the nature of the data, storage requirements, and potential future growth. Using appropriate data types can improve query performance and optimize storage space.


  • Avoid using excessive precision or length in numeric and string data types, as it can lead to unnecessary storage consumption.
  • Be cautious when choosing between VARCHAR and NVARCHAR, as the latter requires double the storage space.
  • Select the appropriate date and time data types based on your specific needs. For example, if you only require dates, using the DATE type instead of DATETIME can save storage space.

In Conclusion

Data types in SQL Server provide a systematic way to define and manage different types of data within your database. By understanding the characteristics and usage scenarios of various data types, you can make informed decisions when designing your database schema and optimizing query performance. Remember to consider factors such as storage requirements and future growth to ensure efficient data management.

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