Get Interactive Reporting For Your Entire Company Easily. The EXISTS operator tests whether a row(s) exists in a subquery. This means that the operator is used together with a subquery.
The Exists operator is said to have been met when at least one row is found in the subquery. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. DROP FUNCTION removes the definition of an existing function. To execute this command the user must be the owner of the function.
PostgreSQL create table if not exists. The argument types to the function must be specifie since several different functions can exist with the same name and different argument lists. This is an extension from the SQL standar which does not allow zero-column tables.
SELECT FROM tabWHERE col= tab1. The following query will retrieve records from items table based on company table. Common Table Expressions are temporary in the sense that they only exist during the execution of the query.
With the EXISTS condition, you can make the DELETE more complex. Sometimes, there may be a need to delete records in one table based on records in another table. You will see that FROM clause does not allow you to list records from more than one table when performing delete, the EXISTS clause becomes very useful.