Chapter 9 SQL Statements
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If you specify a user ID, the option value applies to that user (or, for a group
user ID, the members of that group). If you specify PUBLIC, the option
value applies to all users who don’t have an individual setting for the option.
By default, the option value applies to the currently logged on user ID that
issued the SET OPTION statement..
For example, the following statement applies an option change to the user
DBA, if DBA is the user issuing the SQL statement:
SET OPTION login_mode = mixed
However the following statement applies the change to the PUBLIC user ID,
a user group to which all users belong.
SET OPTION Public.login_mode = standard
Only users with DBA privileges have the authority to set an option for the
PUBLIC user ID.
In embedded SQL, database options can be set only temporarily.
Users can use the SET OPTION statement to change the values for their own
user ID. Setting the value of an option for a user id other then your own is
permitted only if you have DBA authority.
Adding the TEMPORARY keyword to the SET OPTION statement changes
the duration that the change takes effect. By default, the option value is
permanent: it will not change until it is explicitly changed using the SET
OPTION statement.
When the SET TEMPORARY OPTION statement is not qualified with a
user ID, the new option value is in effect only for the current connection.
When SET TEMPORARY OPTION is used for the PUBLIC user ID, the
change is in place for as long as the database is running. When the database
is shut down, TEMPORARY options for the PUBLIC group revert back to
their permanent value.
Setting temporary options for the PUBLIC user ID offers a security benefit.
For example, when the LOGIN_MODE option is enabled, the database relies
on the login security of the system on which it is running. Enabling it
temporarily means that a database relying on the security of a Windows NT
domain will not be compromised if the database is shut down and copied to a
local machine. In that case, the temporary enabling of the LOGIN_MODE
option reverts to its permanent value, which could be Standard, a mode
where integrated logins are not permitted.
If option-value is omitted, the specified option setting will be deleted from
the database. If it was a personal option setting, the value will revert back to
the PUBLIC setting. If a TEMPORARY option is deleted, the option setting
will revert back to the permanent setting.
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