SQL System Functions
System functions are built-in functions that perform operations based on the system, database, or user context. They provide information about the current session, database, or system settings.
General System Functions
DB_NAME() SQL Function
Returns the name of the current database or a specified database ID.
Syntax: DB_NAME ( [ database_id ] )
Description: If an integer is specified, DB_NAME() returns the database name corresponding to that database ID. If no integer is specified, it returns the name of the current database. If the specified ID does not have a name, this function returns NULL.
SELECT DB_NAME() AS CurrentDatabaseName;USER_NAME() SQL Function
Returns the user ID associated with the specified user name or the user name associated with the specified user ID.
Syntax: USER_NAME ( [ user_id ] )
Description: If no argument is specified, USER_NAME() returns the name of the current user. If a user ID is specified, it returns the user name for that ID. If the specified ID does not exist, it returns NULL.
SELECT USER_NAME() AS CurrentUserName;HOST_NAME() SQL Function
Returns the network login name of the client.
Syntax: HOST_NAME ( )
Description: HOST_NAME() returns the name of the workstation that is currently running the client application. This is not necessarily the computer name of the client.
SELECT HOST_NAME() AS ClientHostName;SYSTEM_USER SQL Variable
Returns the login name of the user and the name of the server or database to which the user is connected.
Syntax: SYSTEM_USER
Description: This global variable contains the effective login name. For SQL Server logins, this is typically the login name. For Windows users, it is in the format 'DOMAIN\User'.
SELECT SYSTEM_USER AS ServerLoginInfo;Metadata and Information Functions
@@ROWCOUNT SQL Variable
Returns the number of rows affected by the last statement.
Syntax: @@ROWCOUNT
Description: @@ROWCOUNT is a global variable that holds the number of rows affected by the previous Transact-SQL statement.
UPDATE Employees SET Salary = Salary * 1.10 WHERE Department = 'Sales';
SELECT @@ROWCOUNT AS RowsAffected;@@SERVERNAME SQL Variable
Returns the name of the local server.
Syntax: @@SERVERNAME
Description: @@SERVERNAME returns the name of the server as it is registered in SQL Server. This can be the local server name or the fully qualified domain name (FQDN).
SELECT @@SERVERNAME AS ServerInstanceName;OBJECT_ID() SQL Function
Returns the object identification number of a schema-scoped object.
Syntax: OBJECT_ID ( '[ schema_name. ] object_name' [ , 'object_type' ] )
Description: Returns the ID for a database object, such as a table, view, or stored procedure. If the object does not exist or the user does not have permission to view it, it returns NULL.
SELECT OBJECT_ID('Customers', 'U') AS CustomerTableID;Date and Time System Functions
GETDATE() SQL Function
Returns the current database system timestamp.
Syntax: GETDATE ( )
Description: GETDATE() returns the current date and time as a datetime value. The value is the current date and time when the statement is executed.
SELECT GETDATE() AS CurrentSystemDateTime;SYSDATETIME() SQL Function
Returns the date and time of the server. This value is a server-level value.
Syntax: SYSDATETIME ( )
Description: SYSDATETIME() returns a date and time value that is the current date and time of the computer where the SQL Server instance is running. The precision is up to the hundred-nanosecond.
SELECT SYSDATETIME() AS CurrentServerDateTimeWithHighPrecision;Explore the specific categories of system functions for detailed information and usage examples.