Check for items that contain a value.
Syntax expression IS NOT NULL; Key Expression may be a column_name or a calculated value.
Return all the receipts where the delivery date is NOT null (so it has been delivered on one date or another)
SQL> select * from receipts
where delivery_date IS NOT NULL;
Return all the addresses where the zip code is NOT null (so they do have a zip code)
SQL> select * from addresses
where zip_code IS NOT NULL;
This can also be used in PL/SQL in much the same way: IF myvariable IS NOT NULL then…
“I call it my billion-dollar mistake. It was the invention of the null reference in 1965” ~ Tony Hoare
Oracle SQL Functions
IS NULL - Check for NULL (empty) values
ORA-00932 inconsistent datatypes