Oracle updating through a view dating sites for north american men

As far as the user is concerned, the view looks just like a table.

The following Transact-SQL statement selects all the data for the view shown in Listing 9.1, sorting the result set on the Company Name column: statement wouldn't have to change. Company Name Views are created inside individual databases, however, views can reference tables and views in other databases or even on other servers (if the view is defined using distributed queries).

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CREATE OR REPLACE VIEW Film Details View (Film_Name, Actor_Full Name, Hall_Number, Date_Time) AS SELECT flm.film_name, actor.actor_name || ' ' || actor.actor_surname, hall.cinemahall_number, schedule.schedule_date FROM film flm JOIN movieschedule schedule ON (flm.film_id = schedule.schedule_filmid) JOIN cinemahall hall ON (schedule.schedule_hallid = hall.cinemahall_id) JOIN Film Actor filmactor ON (flm.film_id = filmactor.filmactor_filmid) JOIN Actor actor ON (actor.actor_id = filmactor.filmactor_actorid); Error starting at line 312 in command: UPDATE FILMDETAILSVIEW SET ACTOR_FULLNAME = 'a' WHERE HALL_NUMBER = 1 Error at Command Line:313 Column:4 Error report: SQL Error: ORA-01733: virtual column not allowed here 01733.

00000 - "virtual column not allowed here" *Cause: *Action: A view is just a stored query -- when you update through it, it's the underlying tables that must be modified.

Since you can't list more than one table in the Oracle UPDATE statement, you can use the Oracle EXISTS clause.

Views are saved SELECT statements that allow you to operate on the results that are returned from them.

Another limitation of views that you may be familiar with is that a view cannot be indexed. In SQL Server 2000, you can indeed create indexed views, as shown later in this chapter.

Views still, however, don't allow you to perform any of the other major SQL actions besides selecting—views can't contain syntax when defining a view.

A view can be used to wrap up complex queries containing subqueries, outer joins, and aggregation. Another problem you'll encounter with Access projects (ADPs) is that if you want users to be able to update data using a view, you also have to grant them permissions on the underlying tables.

This simplifies access to the data because the underlying query does not have to be written on the client and then submitted each time a report is run. Although you can set column-level security in SQL Server, it is tricky to maintain because it's pretty well buried in the table properties.

Views can also reference functions and other views.

A user can query a single view instead of having to learn complex join syntax and understand the structure of your database.

That is not possible--you need to instead change the definition of the view.

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