Oracle triggers in the detailed

Oracle Triggers Category:

1. Statement triggers

2, row triggers

3. System Condition Trigger

4. User event triggers

5. INSTEAD of Triggers

1. Statement triggers

is a specific statement or a trigger on a statement group that executes on a table or on a view in some cases. The ability to insert, UPDATE,

Delete or associate on a combination. However, no matter what combination is used, the individual statement triggers are activated only once for the specified statement

。 For example, an UPDATE statement trigger is invoked only once, regardless of how many rows are being update.

Example:

Users who perform DML operations on a table need to be checked for appropriate privileges.

Create Table Foo (a number);

Create Trigger Biud_foo

Before insert or UPDATE or delete

on Foo

Begin

If user not in (' DONNY ') then

Raise_application_error ( -20001, ' don ' t have access to modify this table. ');

End If;

End;

/

Even Sys,system users cannot modify the Foo table

Test

Log the time and character of the modified table.

1, the establishment of the test table

CREATE TABLE employees_copy as select *from hr.employees

2, the establishment of the log table

CREATE TABLE Employees_log (

Who Varchar2 (30),

When date);