Firebird 2.1 Language Reference Update

Internal functions
Table 12.3. Context variables in the SYSTEM namespace
DB_NAME Either the full path to the database or – if connecting via the path is disallowed
– its alias.
NETWORK_PROTOCOL The protocol used for the connection: 'TCPv4', 'WNET', 'XNET' or NULL.
CLIENT_ADDRESS For TCPv4, this is the IP address. For XNET, the local process ID. For all other
protocols this variable is NULL.
CURRENT_USER Same as global CURRENT_USER variable.
CURRENT_ROLE Same as global CURRENT_ROLE variable.
SESSION_ID Same as global CURRENT_CONNECTION variable.
TRANSACTION_ID Same as global CURRENT_TRANSACTION variable.
ISOLATION_LEVEL The isolation level of the current transaction: 'READ COMMITTED', 'SNAPSHOT'
or 'CONSISTENCY'.
Return values and error behaviour: If the polled variable exists in the given namespace, its value will be returned
as a string of max. 255 characters. If the namespace doesn't exist or if you try to access a non-existing variable
in the SYSTEM namespace, an error is raised. If you poll a non-existing variable in one of the other namespaces,
NULL is returned. Both namespace and variable names must be given as single-quoted, case-sensitive, non-NULL
strings.
Examples:
select rdb$get_context('SYSTEM', 'DB_NAME') from rdb$database
New.UserAddr = rdb$get_context('SYSTEM', 'CLIENT_ADDRESS');
insert into MyTable (TestField)
values (rdb$get_context('USER_SESSION', 'MyVar'))
See also: RDB$SET_CONTEXT()
Note
RDB$SET_CONTEXT()
RDB$SET_CONTEXT and its counterpart RDB$GET_CONTEXT are actually predeclared UDFs. They are listed
here as internal functions because they are always present – the user doesn't have to do anything to make them
available.
Available in: DSQL, ESQL, PSQL
Added in: 2.0
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