Task: Text to Code
Input (English): Step 1: For each row in Invoices table, find corresponding rows in Customer_Orders table and in Invoice_Items table.
Step 2: find Order_Date of the results of step 1 whose Invoice_Items's Order_Quantity equals 1
Output (English): SELECT T1.Order_Date FROM Customer_Orders AS T1 JOIN Invoices AS T2 ON T1.Order_ID = T2.Order_ID JOIN Invoice_Items AS T3 ON T2.Invoice_ID = T3.Invoice_ID WHERE T3.Order_Quantity = 1