Querying correlated data
You can query one table relative to the data in another table.
Select all state and net_payments values from the transfer_payments table for years during which the value of the state column in the transfer_payments table matches the value of the state column in the us_census table.
SELECT state, net_payments FROM transfer_payments WHERE EXISTS (SELECT year FROM us_census WHERE transfer_payments.state = us_census.state);
This query is correlated because one side of the equals predicate operator in the subquery references the state column in the transfer_payments table in the parent query and the other side of the operator references the state column in the us_census table.
This statement includes a conjunct in the WHERE clause.
A conjunct is equivalent to the AND condition, while a disjunct is the equivalent of the OR condition The following subquery contains a conjunct:
... WHERE transfer_payments.year = "2018" AND us_census.state = "california"
The following subquery contains a disjunct:
... WHERE transfer_payments.year = "2018" OR us_census.state = "california"