Updating table in oracle online dating for deaf people
When I try to update only the missing data the non-matched data is also updated but to NULL. The reason some of your rows are getting NULLs updated is due to the subquery.
When the subquery fails to find a matching row in tbl B, the subquery returns NULL.
a delete statement that affects more than one row).
As we noted before, the INSTEAD OF trigger is implicitly for each row.
The returning clause retrieves the rows affected by a DML statement.
You can specify this clause for tables and materialized views and for views with a single base table.
Example use case: I have a database that contains a table of contacts (contact) and table of e-mail addresses (email), joined on = email.contact_id.
This works fine when I try to update all the records in tbl A, however, in this case I only have missing data which I have identified and populated in tbl B.
When used in the subquery of a DML statement, you can specify this clause in a subquery in the can be a subquery, a column, a function, or a collection constructor.