Updating a join view oracle americasexx 100
The illustration in Figure 1 below shows an item master table from Application A along with a supplemental custom item extension table; this table, as the name suggsts, provides supplemental columns not provided by the application’s Item Master.
While it is relatively easy to retrieve and modify the data from both tables using RPG and subfiles, it is not so easy to do with SQL, especially in a client/server application.
Allowing the Item Master fields to be updated, if desired, is an added bonus.
Yet another benefit to using INSTEAD OF triggers is that database programmers can maintain complex update code within their own realm while supplying a single table, which is easier than stored procedures, for client side programmers to use.
Item; Delete From Item Ext Where Item=Item View Old. Weight); End; Create Trigger DATALIB/ITEMUPDATE Instead Of Update On DATALIB/ITEMVIEW Referencing Old As Item View Old New As Item View New For Each Row Mode DB2SQL Begin Atomic Update Item Master Set Item=Item View New. This handy feature allows an i Series (or other remote database) table or view to be updated by Microsoft’s Access database.
Of course this is just one possibility, as we could have just as easy coded the “delete” trigger to actually update a deleted flag column to ‘Y’ in the base tables. The beauty here is that both related tables are present in a single form and can be updated simultaneously.) On the i Series, limited support for INSTEAD OF triggers was delivered by PTF SI16101 for i5/OS V5R3 systems. Many PC developer tools–for example, those that come with Visual Studio .Unfortunately, data manipulation against multi-table views involving Joins or Unions was not yet supported, limiting their usefulness to single table views. The examples shown in this story were originally developed on DB2 UDB for Windows V8.2.1 and required very little modification to run on the i Series. NET–can be used to build code for creating updateable Windows forms or Web pages based on a single table but cannot do so against multiple table views (without lots of extra code).(MSDN: MERGE Transact-SQL) Here is a side-by-side comparison of the MERGE and UPDATE statements: In this side by side comparison you can see the similarities key areas of these statements: With MERGE, you’re able to combine update, delete, and insert command into one statement. This is because the MERGE statement uses a WHEN clause to determine the course of action to take on the match.
By creating INSTEAD OF triggers on update and insert events, view ITEMVIEW will become fully modifiable. Item Type); Insert Into Item Ext Values(Item View New. The form would not be nearly as effective if it showed, for example, only the item extension data.