SQL Server Security Functions

Security functions return information about users and roles. Security functions return information that is userful in managing security.

Function	Description	Syntax
CURRENT_USER	Returns the name of the current user. This function is equivalent to USER_NAME().	CURRENT_USER
sys.fn_builtin_permissions	Returns a description of the built-in permissions hierarchy of the server.	sys.fn_builtin_permissions ( [ DEFAULT | NULL ] | <empty_string> | '<securable_class>' )
fn_my_permissions	Returns a list of the permissions effectively granted to the principal on a securable. A related function is HAS_PERMS_BY_NAME.	fn_my_permissions ( <securable>, '<securable_class>' )
HAS_PERMS_BY_NAME	Evaluates the effective permission of the current user on a securable. A related function is fn_my_permissions.	HAS_PERMS_BY_NAME ( <securable>, <securable_class> <permission> [ , <sub-securable> ] [ , <sub-securatble_class> ] )
IS_MEMBER	Indicates whether the current user is a member of the specified Microsoft Windows group or Microsoft SQL Server database role.	IS_MEMBER ( { '<group>' | '<role>' } )
IS_SRVROLEMEMBER	Indicates whether a SQL Server login is a member of the specified fixed server role.	IS_SRVROLEMEMBER ( '<role>' [ , '<login>' ] )
PERMISSIONS	Returns a value containing a bitmap that indicates the statement, object or column permissions of the current user.	PERMISSIONS ( [ <objectid> [ , '<column>' ] ] )
SCHEMA_ID	Returns the schema ID associated with a schema name.	SCHEMA_ID ( [ <schema_name> ] )
SCHEMA_NAME	Returns the schema name associated with a schema ID.	SCHEMA_NAME ( [ <schema_id> ] )
SESSION_USER	Returns the user name of the current context in the current database.	SESSION_USER
SETUSER	Allows a member of the sysadmin fixed server role of db_owner fixed database role to impersonate another user.	SETUSER [ '<username>' [ WITH NORESET ] ]
SUSER_ID	Returns the login identification number of the user.	SUSER_ID ( [ '<login>' ] )
SUSER_SID	Returns the security identification number (SID) for the specified login name.	SUSER_SID ( [ '<login>' ] )
SUSER_SNAME	Returns the login name associated with a security identification number (SID).	SUSER_SNAME ( [ <server_user_id> ] )
SYSTEM_USER	Allows a system-supplied value for the current login to be inserted into a table when no default value is specified.	SYSTEM_USER
SUSER_NAME	Returns the login identification name of the user.	SUSER_NAME ( [ <server_user_id> ] )
USER_ID	Returns the identification number for a database user.	USER_ID ( [ '<user>' ] )
USER_NAME	Returns a database user name from a specified identification number.	USER_NAME ( [ '<id>' ] )