Before INSERT or Update trigger plsql?

You can easily do what you want with CHECK CONSTRAINT on your column ALTER TABLE T ADD CONSTRAINT constraint_name CHECK (location 'chicago') DISABLE The DISABLE keyword is optional. If you create a check constraint using the DISABLE keyword, the constraint will be created but the condition will not be enforced Constraint States ENABLE ensure that all incoming data conforms to the constraint DISABLE allow incoming data, regardless of whether it conforms to the constraint VALIDATE ensure that existing data conforms to the constraint NOVALIDATE existing data does not have to conform to the constraint These can be used in combination ENABLE { default VALIDATE | NOVALIDATE } DISABLE { VALIDATE |default NOVALIDATE } ENABLE VALIDATE is the same as ENABLE ENABLE NOVALIDATE means that the constraint is checked, but it does not have to be true for all rows. This will resume constraint checking on disabled constraints without first validating all data in the table DISABLE NOVALIDATE is the same as DISABLE DISABLE VALIDATE disables the constraint, drops the index on the constraint, and disallows any modification of the constrained columns.

For a UNIQUE constraint, this enables you to load data from a nonpartitioned table into a partitioned table using the ALTER TABLE.. EXCHANGE PARTITION clause Here is an example of BEFORE INSERT trigger. However it is better to create constraints on your schema or to implement CUSTOM_INSERT PROCEDURE, to filter it Here is a good article about Data Integrity - Constraints and Triggers Triggers should not be used to enforce business rules or referential integrity rules that could be implemented with simple constraints Example trigger(consider it as a bad idea for filtering input): CREATE TRIGGER myTrigger BEFORE INSERT ON table REFERENCING NEW AS New FOR EACH ROW BEGIN IF (New. Location = 'chicago') THEN RAISE cError; EXCEPTION WHEN cError THEN RAISE_APPLICATION_EXCEPTION(-20001,'Chicago is not allowed'); END.

You can easily do what you want with CHECK CONSTRAINT on your column. ALTER TABLE T ADD CONSTRAINT constraint_name CHECK (location 'chicago') DISABLE; The DISABLE keyword is optional. If you create a check constraint using the DISABLE keyword, the constraint will be created, but the condition will not be enforced.

Constraint States ENABLE - ensure that all incoming data conforms to the constraint DISABLE - allow incoming data, regardless of whether it conforms to the constraint VALIDATE - ensure that existing data conforms to the constraint NOVALIDATE - existing data does not have to conform to the constraint These can be used in combination ENABLE { default VALIDATE | NOVALIDATE } DISABLE { VALIDATE |default NOVALIDATE } ENABLE VALIDATE is the same as ENABLE. ENABLE NOVALIDATE means that the constraint is checked, but it does not have to be true for all rows. This will resume constraint checking on disabled constraints without first validating all data in the table.

DISABLE NOVALIDATE is the same as DISABLE. DISABLE VALIDATE disables the constraint, drops the index on the constraint, and disallows any modification of the constrained columns. For a UNIQUE constraint, this enables you to load data from a nonpartitioned table into a partitioned table using the ALTER TABLE.. EXCHANGE PARTITION clause.

Here is an example of BEFORE INSERT trigger. However it is better to create constraints on your schema or to implement CUSTOM_INSERT PROCEDURE, to filter it. Here is a good article about Data Integrity - Constraints and Triggers.

Triggers should not be used to enforce business rules or referential integrity rules that could be implemented with simple constraints. Example trigger(consider it as a bad idea for filtering input): CREATE TRIGGER myTrigger BEFORE INSERT ON table REFERENCING NEW AS New FOR EACH ROW BEGIN IF (New. Location = 'chicago') THEN RAISE cError; EXCEPTION WHEN cError THEN RAISE_APPLICATION_EXCEPTION(-20001,'Chicago is not allowed'); END.

Instead of DELETE there should be RAISE_APPLICATION_ERROR(-20000,'No Chicago, please! '); – jva Aug 24 '09 at 9:50 The whole trigger thing is not needed at all.. And in my examle (bad one) the trigger is after... – Svetlozar Angelov Aug 24 '09 at 10:12 1 The disadvantage of a trigger is that you'd have to fail the statement. With a check constraint, the developer has the option of of using a LOG ERRORS clause so that valid data gets inserted and the invalid data gets put into an exception table.

Very useful for bulk data loads. – Gary Myers Aug 24 '09 at 12:28 1 Worth adding that there is a NOVALIDATE caluse for check constraints to, so that the constraint is enforced for new inserts, but existing 'invalid' data can remain in the table (eg if you have closed the Chicago office, the historic data can stay, but you won't get any new data) – Gary Myers Aug 24 '09 at 12:30 Good remark! "ENABLE NOVALIDATE means that the constraint is checked, but it does not have to be true for all rows.

This will resume constraint checking on disabled constraints without first validating all data in the table. " – Svetlozar Angelov Aug 24 '09 at 12:38.

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