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SQL> DELETE FROM product_user_profile WHERE userid='OE' and attribute = 'DELETE'; 1 row deleted. SQL> COMMIT; Commit complete. SQL> The ALTER, BEGIN, DECLARE, EXECUTE, and GRANT commands are data definition language (DDL) and PL/SQL commands. The INSERT, SELECT, and UPDATE commands are, of course, data manipulation language (DML) commands. The HOST command is used in SQL*Plus to access the operating system and issue operating system commands. You really don t want your users to be able to issue operating system commands by simply using the HOST command, so if you want to deny user salapati this dangerous privilege, this is what you have to do to the product_user_profile table: SQL> INSERT INTO product_user_profile (product,userid,attribute) VALUES ('SQL*Plus','salapati','HOST'); 1 row created. SQL> If you want to restore to user salapati the right to use the HOST command, you can do so by deleting the row you just inserted. For example, you would need to issue the following command to restore the HOST privilege to user salapati: SQL> DELETE FROM product_user_profile WHERE userid='SALAPATI';

Note Remember that users will retain any privileges you grant them, even though they can t exercise the privileges in the SQL*Plus session. This means you can grant application owners privileges on the data objects when they are using packages and procedures that are stored and executed in the database, while at the same time denying them these same privileges when they log into SQL*Plus.

As you probably know, it is better to grant and revoke database privileges through the use of roles, rather than granting the privileges directly, for several reasons. The use of roles, however, carries with it a potential security problem, because any user can change his or her role by simply using the set role command in SQL*Plus. You can shut down this security loophole by using the product_ user_profile table to disable any user s ability to use the set role command.

As an alternative to using the product_user_profile table, you can use the RESTRICT command to prevent users from using certain operating system commands. The net effect is the same as using the product_user_profile table, except that the RESTRICT command disables the commands even where there are no connections to the server. You can use the RESTRICT command at three levels Level 1, Level 2, and Level 3. The following example illustrates the use of the command at Level 1: $ sqlplus -RESTRICT 1

Table 4-1 shows the commands that are disabled by using th RESTRICT command and the differences among the three restriction levels.

If you issue the RESTRICT -3 command, Oracle doesn t read the login.sql script. It reads the glogin.sql script, and any restricted commands that are used will not work.

Of all the commands that you can use in SQL*Plus, the SET command is probably the most fundamental, because it enables you to set the all-important environment for your SQL*Plus sessions. Environment settings include the number of lines per page of output, the width of the numeric data in the output, the titles for reports, and the HTML formatting, all of which are enabled, disabled, or modified with the SET command. The SET command is but one of the commands that you can use in SQL*Plus, and you can see the entire list of available commands by typing help index at the SQL prompt, as shown in Listing 4-3. Listing 4-3. Using the HELP INDEX Command to Show Help Topics SQL> HELP INDEX Enter Help [topic] for help. @ COPY @@ DEFINE / DEL ACCEPT DESCRIBE APPEND DISCONNECT ARCHIVE LOG EDIT ATTRIBUTE EXECUTE BREAK EXIT BTITLE GET CHANGE HELP CLEAR HOST COLUMN INPUT COMPUTE LIST CONNECT PASSWORD

PAUSE PRINT PROMPT QUIT RECOVER REMARK REPFOOTER REPHEADER RESERVED WORDS(SQL) RESERVED WORDS(PL/SQL) RUN SAVE SET SHOW

SHUTDOWN SPOOL SQLPLUS START STARTUP STORE TIMING TTITLE UNDEFINE VARIABLE WHENEVER OS_ERROR WHENEVER SQLERROR