CREATE TABLE Accounts (customer_id VARCHAR2)
CREATE TABLE Customers (customer_first_name VARCHAR2, customer_id VARCHAR2)

Show first name and id for all customers with at least 2 accounts.
SELECT T2.customer_first_name, T1.customer_id FROM Accounts AS T1 JOIN Customers AS T2 ON T1.customer_id = T2.customer_id GROUP BY T1.customer_id HAVING COUNT(*) >= 2
SELECT "T2"."customer_first_name", "T1"."customer_id" FROM "Accounts" "T1" JOIN "Customers" "T2" ON "T1"."customer_id" = "T2"."customer_id" GROUP BY "T1"."customer_id" HAVING COUNT(*) >= 2