If you define a view with an outer join, then query the view with a qualification on a column from the inner table of the outer join, the results may not be what you expect. The query returns all rows from the inner table. Rows that do not meet the qualification show a null value in the appropriate columns of those rows.
The following rules determine what types of updates you can make to columns through join views:
delete statements are not allowed on join views.
insert statements are not allowed on join views created with check option.
update statements are allowed on join views with check option. The update fails if any of the affected columns appear in the where clause, in an expression that includes columns from more than one table.
If you insert or update a row through a join view, all affected columns must belong to the same base table.
