ORA-12081
An user tried to update some data in a table (DML), but it failed with ORA-12081.
SQL> update employees set first_name = 'Scott' where last_name = 'Rowe';
update employees set first_name = 'Scott' where last_name = 'Rowe'
*
ERROR at line 1:
ORA-12081: update operation not allowed on table "HR"."EMPLOYEES"
Even SELECT FOR UPDATE failed with this error.
SQL> select employee_id from employees for update;
select employee_id from employees for update
*
ERROR at line 1:
ORA-12081: update operation not allowed on table "HR"."EMPLOYEES"
ORA-12081 means that the table you want to update is READ ONLY which does not allow doing operations of modifying the data in the table. Which means, you can still change the definition of the table as long as data is intact as promised.
Solution
Let's see what mode of the table currently is.
SQL> select read_only from all_tables where owner = 'HR' and table_name = 'EMPLOYEES';
REA
---
YES
The positive result shows us that READ ONLY of this table is enabled.
The solution to ORA-12081 is to have the table back to READ WRITE. Otherwise, no modifying operation on the data is allowable.