Which statement creates an index on orders(customer_id) with the name idx_orders_customer_id?

• A. CREATE UNIQUE INDEX idx_orders_customer_id ON orders (customer_id)
• B. CREATE INDEX ON orders (customer_id)
• C. CREATE INDEX idx_orders_customer_id ON customers (customer_id)
• D. CREATE INDEX idx_orders_customer_id ON orders (customer_id)

Answer: (D)

The statement tests how to create a named index on a specific table and column using the standard syntax: CREATE INDEX index_name ON table_name (column_list). The correct form names the index idx_orders_customer_id, targets the orders table, and indexes the customer_id column, exactly as required: CREATE INDEX idx_orders_customer_id ON orders (customer_id). By default this creates a non-unique index, which matches the request unless a UNIQUE constraint is specified. The other options either try to enforce uniqueness, omit the index name, or apply the index to the wrong table, so they don’t fit the stated requirement.