CREATE TABLE checking (balance NUMBER)
CREATE TABLE accounts (name VARCHAR2, custid VARCHAR2)

Find the name of accounts whose checking balance is below the average checking balance.
SELECT T1.name FROM accounts AS T1 JOIN checking AS T2 ON T1.custid = T2.custid WHERE T2.balance < (SELECT AVG(balance) FROM checking)
SELECT "T1"."name" FROM "accounts" "T1" JOIN "checking" "T2" ON "T1"."custid" = "T2"."custid" AND "T2"."balance" < (SELECT AVG("balance") FROM "checking")