Insert data after simple Oracle judgment

Sometimes using Oracle's database, you need to judge when inserting data. For example, each person can only write one article per day.
In the insertion of the time to make a judgment, check whether there is a person on the day of the operation of the record.
Will first

1.select Count (*) from XXX

A moment.
This day checked, there is a way to do without first select
was supposed to be

The code is as follows	Copy Code
1.insert 2.into form (Formid) VALUES (111)

Change into

The code is as follows	Copy Code
1.insert 2.when (Not EXISTS (select 1 from form where formid =)) Then 3.into form (formid) select from dual

In this way, when there is a formid=111 record in the database, the insert operation is not performed.