What is the SQL Server SYSNAME Data Type and How Is It Used?

Understanding the SYSNAME Data Type in SQL Server

The SYSNAME data type in SQL Server is designed for storing object names in database tables, variables, and stored procedure parameters. While the documentation provides a broad definition, the purpose of SYSNAME may not be immediately clear.

What it is Used for

Primarily, SYSNAME is employed to reference database object names, such as in the outputs of system procedures like sp_help, where column names are declared as SYSNAME because they represent actual objects within the database.

Equivalence and Usage

Functionally, SYSNAME is akin to nvarchar(128) NOT NULL. It can be defined with a colation by specifying a COLLATE clause when using it, e.g., SYSNAME COLLATE Latin1_General_CI_AS to set the collation to case-insensitive.

Nullable and Non-Nullable

By default, SYSNAME is defined as NON-NULL, but it is possible to specify NULL when defining a column or variable to allow for null values. However, it's important to note that the definition of SYSNAME may vary across different SQL Server instances.

Additional Information

In earlier versions of SQL Server (6.5 and below), SYSNAME was defined as VARCHAR(30). However, in modern versions, it is equivalent to nvarchar(128), unless explicitly specified otherwise.

Despite its usefulness for referencing object names, the SYSNAME data type is primarily used by Microsoft in the construction of internal system tables and stored procedures. In day-to-day development, it is uncommon to encounter SYSNAME outside of these contexts.

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