我如何在mysql中加入4表

Question

我想加入4表来检索customer_name，product_name，order_qty，order_amount;

Answer 1

对于LEFT JOIN尝试以下

SELECT * FROM customer AS cm 
LEFT JOIN sales_order AS so ON cm.customer_id=so.customer_id
LEFT JOIN sales_order_detail AS sod ON so.sales_order_id=sod.sales_order_id
LEFT JOIN product AS pd ON sod.sales_order_id=pd.sales_order_id