Defining the schema of tables for clients and their orders

Formulate SQL operators that create two tables.

Table customers:

• id — unique identifier (PRIMARY KEY, auto-generated, SERIAL).
• name — customer's name (TEXT, NOT NULL).

Table purchases:

• id — unique order identifier (PRIMARY KEY, auto-generated, SERIAL).
• customer_id — foreign key referencing the customers table (INTEGER, NOT NULL).
• purchase_date — date of order placement (TIMESTAMP, NOT NULL).

The foreign key customer_id should reference the id field of the customers table.