To find records in one table that aren't in another, you can use a LEFT JOIN and check for NULL values in the right-side table. Here is an example using two tables, oracle_employees and oracle_managers: SELECT * FROM oracle_employees LEFT JOIN oracle_managers ON oracle_employees.id = oracle_managers.id WHERE oracle_managers.id IS NULL; This will return all rows from oracle_employees where there is no matching row in managers based on the id column. You can also use the EXCEPT operator in PostgreSQL and Microsoft SQL Server to return the records that are in the first table but not in the second. Here is an example: SELECT * FROM oracle_employees EXCEPT SELECT * FROM oracle_managers This will retrieve all rows from employees that do not appear in managers. The EXCEPT operator works by retrieving the rows that are returned by the first query, but not by the second. Please note that EXCEPT is not supported by all DBMS systems, such as MySQL and Oracle (however, you can use the MINUS operator to achieve a similar outcome). ---