In Oracle, NOT EXISTS operator allows you to check non existence of any record in a subquery. The NOT EXISTS operator can be used in a SELECT, INSERT, UPDATE, or DELETE statement.
To check non existence of any record in a subquery, use the following syntax:
Parameters:
tablename: The table name from which you want to perform NOT EXISTS operator.
subquery: Usually a SELECT statement starts with SELECT * or column name. Oracle ignores the SELECT list from subquery.
Note:
In the above example, the NOT EXISTS operator will return all records from the "tblbankdemataccountcharges" table where there is no record in the tblbankheadquartersandaddress table with the matching "bankId".