Oracle if updating trigger dating wizards ebook
The particular strength in question here is that of having a read consistent view of data.It is worthwhile to note that this ORA-04091 error occurs not only in the "pure" database development environment, but also in the Oracle tools type of development environment such as Oracle SQL*Forms. UPDATE bank_transactions SET txn_number = 'NEWTXN8080' WHERE txn_id = 1; UPDATE bank_transactions SET txn_number = 'NEWTXN9595' WHERE txn_id = 2; -- output 1 rows updated. Dhaval Dadhaniya is a software engineer by profession and reader/writter by passion. CREATED_DATE); END; --Inserting values INSERT INTO BANK_TRANSACTIONS values ('1','TXN1234','Peter Thomas','12-MAY-2017','HR',sysdate); INSERT INTO BANK_TRANSACTIONS values ('2','TXN9999','Jemes Patel','10-JUN-2016','HR',sysdate); select * from BANK_TRANSACTIONS; --updating values.CREATE OR REPLACE TRIGGER CHK_SALES_JOB BEFORE INSERT OR UPDATE OF JOB_ID ON EMPLOYEES FOR EACH ROW BEGIN IF :old.department_id = 80 AND (:new.job_id ! = 'SA_MAN') THEN RAISE_APPLICATION_ERROR(-20001, 'Sales Department can only have SA_MAN or SA_REP'); END IF; END; If I have the OR condition within the If statement, the code would never work.It will compile the trigger with no problem, but when ever I try to update the employees table, it will continuously display the RAISE_APPLICATION_ERROR. This data can be stored in a PL/SQL collection or in a temporary table.
In many cases, use of the INSTEAD-OF trigger feature allows you to work around these restrictions.However, when a view becomes more complex (multiple tables or views used in various join conditions to create the new single view), there is a good chance that many columns, as referenced by the view, lose their "updateable-ness." So, being the data dictionary view/table name trivia wizard that you are, you know to query the XXX_UPDATABLE_COLUMNS views, substituting USER, ALL or DBA for XXX as applicable.There are exceptions to this rule about views being inherently updateable.A mutation table is defined as a table that is changing.
But in dealing with triggers, it is a table that has the possibility of changing.A trigger that causes other database events to execute triggers can cause the database crash.