CREATE TABLE savings (custid DECIMAL, balance DECIMAL)
CREATE TABLE checking (custid DECIMAL, balance DECIMAL)
CREATE TABLE accounts (custid DECIMAL, name TEXT)

Find the saving balance of the account with the highest checking balance.
SELECT T3.balance FROM accounts AS T1 JOIN checking AS T2 ON T1.custid = T2.custid JOIN savings AS T3 ON T1.custid = T3.custid ORDER BY T2.balance DESC LIMIT 1
SELECT "T3"."balance" FROM "accounts" AS "T1" JOIN "checking" AS "T2" ON "T1"."custid" = "T2"."custid" JOIN "savings" AS "T3" ON "T1"."custid" = "T3"."custid" ORDER BY "T2"."balance" DESC NULLS LAST LIMIT 1