Read-Only Tables in Oracle Database 11g Release 1

In previous Oracle releases, tables could be made to appear read-only to other users by only granting the SELECT object privilege to them, but the tables remained read-write for the owner. Oracle 11g allows tables to be marked as read-only using the ALTER TABLE command.

ALTER TABLE table_name READ ONLY;
ALTER TABLE table_name READ WRITE;

The following script creates a table, inserts a row, then sets the table to read-only.

CREATE TABLE ro_tab (
  id  NUMBER
);

INSERT INTO ro_tab VALUES (1);
ALTER TABLE ro_tab READ ONLY;

Any DML statements that affect the table data and SELECT ... FOR UPDATE queries result in an ORA-12081 error message.

SQL> INSERT INTO ro_tab VALUES (2);
INSERT INTO ro_tab VALUES (2)
            *
ERROR at line 1:
ORA-12081: update operation not allowed on table "TEST"."RO_TAB"


SQL> UPDATE ro_tab SET id = 2;
UPDATE ro_tab SET id = 2
       *
ERROR at line 1:
ORA-12081: update operation not allowed on table "TEST"."RO_TAB"


SQL> DELETE FROM ro_tab;
DELETE FROM ro_tab
            *
ERROR at line 1:
ORA-12081: update operation not allowed on table "TEST"."RO_TAB"

DDL statements that affect the table data are also restricted.

SQL> TRUNCATE TABLE ro_tab;
TRUNCATE TABLE ro_tab
               *
ERROR at line 1:
ORA-12081: update operation not allowed on table "TEST"."RO_TAB"


SQL> ALTER TABLE ro_tab ADD (description VARCHAR2(50));
ALTER TABLE ro_tab ADD (description VARCHAR2(50))
*
ERROR at line 1:
ORA-12081: update operation not allowed on table "TEST"."RO_TAB"

Operations on indexes associated with the table are unaffected by the read-only state. DML and DDL operations return to normal once the table is switched back to read-write mode.

SQL> ALTER TABLE ro_tab READ WRITE;

Table altered.

SQL> DELETE FROM ro_tab;

1 row deleted.

SQL>

The read-only status of tables is displayed in the READ_ONLY column of the [DBA|ALL|USER]_TABLES views.

For more information see:

Hope this helps. Regards Tim...

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