oracle園地

Oracle Forms Triggers

Trigger is a set of statements that executed when an action take a place.

There is some types depends on event level (Form, Block, Record, Item) for Triggers,

觸發器組成:  
    觸發事件：即在何種情況下觸發TRIGGER; 例如：INSERT, UPDATE, DELETE。
    觸發時間：即該TRIGGER 是在觸發事件發生之前（BEFORE）還是之後(AFTER)觸發，也就是觸發事件和該TRIGGER 的操作順序。 
    觸發器本身：即該TRIGGER 被觸發之後的目的和意圖，正是觸發器本身要做的事情。 例如：PL/SQL 塊。
    觸發頻率：說明觸發器內定義的動作被執行的次數。即語句級(STATEMENT)觸發器和行級(ROW)觸發器。

觸發器是一種自動執行響應數據庫變化的程序。可以設置為在觸發器事件之前或之後觸發或執行。能夠觸發觸發器事件的事件包括下面幾種：

　　DML事件
　　DDL事件
　　數據庫事件

Action                 Trigger Firing Order                    Level

------                 --------------------                    -----

Runform                 1.  Pre-Logon                          Form

                        2.  On-Logon                           Form

                        3.  Post-Logon                         Form

                        4.  Pre-Form                           Form

                        5.  When-Create-Record                 Block

                        6.  Pre-Block                          Block

                        7.  Pre-Record                         Block

                        8.  Pre-Text-Item                      Item

                        9.  When-New-Form-Instance             Form

                        10. When-New-Block-Instance            Block

                        11. When-New-Record-Instance           Block

                        12. When-New-Item-Instance             Item

***********

Enter Query             1.  Post-Text-Item                     Item

                        2.  Post-Record                        Block

                        3.  When-Clear-Block                   Block

                        4.  When-New-Record-Instance           Block

                        5.  When-New-Item-Instance             Item

Note: If you define the Key-ENTQRY trigger, this is the only trigger

      which fires in an Enter Query situation.

*****************

Execute Query

After Enter Query       1.  Pre-Query                          Block

                        2.  Pre-Select                         Block

                        3.  On-Select                          Block

                        4.  When-Clear-Block                   Block

                        5.  Post-Select                        Block

                        6.  On-Fetch                           Block

                        7.  On-Close                           Form

                        8.  When-Clear-Block                   Block

Note: If you define the Key-EXEQRY trigger, this is the only trigger

      which fires in an Execute Query situation.

*************

Execute Query

Without Enter

Query                   1.  Post-Text-Item                     Block

                        2.  Pre-Query                          Block

                        3.  Pre-Select                         Block

                        4.  On-Select                          Block

                        5.  Post-Select                        Block

                        6.  On-Fetch                           Block

                        7.  On-Close                           Form

                        8.  When_Create_Record                 Block

                        9.  Pre-Record                         Block

                        10. Pre-Text-Item                      Item

                        11. When-New-Record-Instance           Block

                        12. When-New-Item-Instance             Item

****

Exit                    1.  Post-Text-Item                     Item

                        2.  Post-Record                        Block

                        3.  Post-Block                         Block

                        4.  Post-Form                          Form

                        5.  On-Rollback                        Form

                        6.  Pre-Logout                         Form

                        7.  On-Logout                          Form

                        8.  Post-Logout                        Form

**************

Next Field and

Previous field          1.  When-New-Item-Instance             Item

***************

Next Record and

Previous Record         1.  When-New-Record-Instance           Block

                        2.  When-New-Item-Instance             Item

**************

Next Block and

Previous Block          1.  Post-Text-Item                     Item

                        2.  Post-Record                        Block

                        3.  Post-Block                         Block

                        4.  When-Create-Record                 Block

                        5.  Pre-Block                          Block

                        6.  Pre-Record                         Block

                        7.  Pre-Text-Item                      Block

                        8.  When-New-Block-Instance            Block

                        9.  When-New-Record-Instance           Block

                        10. When-New-Item-Instance             Form

*******************

Records Are Queried     1.  Post-Query                         Block

                        2.  Post-Change                        Block

                        3.  Post-Change                        Item

                        4.  Post-Change                        Block

                        5.  Post-Change                        Block

                        Go back to Post-Query

NOTE: This cycle is repeated for each record retrieved.

**********************

No Records Are Queried  1.  When-New-Record-Instance           Block

                        2.  When-New-Item-Instance             Item

NOTE: To observe this Trigger Firing Order:

        a.  Enter a query.

        b.  Enter a nonexistent record.

        c.  Execute the query.

      The two triggers listed above, the Enter Query triggers, and

      the Execute Query triggers fire.

*************

Create Record           1.  Post-Change                         Block

                        2.  When-Validate-Item                  Block

                        3.  Post-Text-Item                      Block

                        4.  When-Validate-Record                Block

                        5.  Post-Record                         Block

                        6.  Post-Block                          Block

                        7.  On-Savepoint                        Form

                        8.  Pre-Commit                          Form

                        9.  Pre-Insert                          Block

                        10. On-Insert                           Form

                        11. Post-Insert                         Block

                        12. Post-Forms-Commit                   Form

                        13. On-Commit                           Form

                        14. Post-Database-Commit                Form

                        15. Pre-Block                           Block

                        16. Pre-Record                          Block

                        17. Pre-Text-Item                       Block

                        18. When-New-Item-Instance              Form

*************

Update Record           1.  When-Database-Record                Block

                        2.  Post-Change                         Block

                        3.  When-Validate-Item                  Block

                        4.  Post-Text-Item                      Block

                        5.  When-Validate-Record                Block

                        6.  Post-Record                         Block

                        7.  Post-Block                          Block

                        8.  On-Savepoint                        Form

                        9.  Pre-Commit                          Form

                        10. Pre-Update                          Block

                        11. On-Update                           Block

                        12. Post-Update                         Block

                        13. Post-Forms-Commit                   Form

                        14. On-Commit                           Form

                        Here the transaction is complete and one record added.

                        15. Post-Database-Commit                Form

                        16. Pre-Text-Item                       Block

                        17. When-New-Item-Instance              Form

NOTE: To observe this Trigger Firing Order:

        a.  Execute a query.

        b.  Change a value.

        c.  Choose Action->Save from the menu.

        d.  Record the triggers from that point.

*************

Delete Record           1.  On-Lock                             Block

                        2.  When-Remove-Record                  Block

                        3.  Post-Change                         Block

                        4.  Post-Change                         Block

                        5.  Post-Change                         Block

                        6.  Post-Change                         Block

                        7.  Post-Change                         Block

                        8.  Post-Change                         Block

                        9.  Post-Change                         Item

                        10. Post-Query                          Block

                        11. Post-Text-Item                      Block

                        12. Post-Record                         Block

                        13. Pre-Record                          Block

                        14. Pre-Text-Item                       Block

                        15. When-New-Record-Instance            Block

                        16. When-New-Item-Instance              Form

NOTE: To observe this Trigger Firing Order, delete a detail record.