The ORDERS table has a primary key constraint on the ORDER_ID column.
The ORDER_ITEMS table has a foreign key constraint on the ORDER_ID column,referencing the primary key of the ORDERS table.
The constraint is defined with on DELETE CASCADE.
There are rows in the ORDERS table with an ORDER_TOTAL less than 1000.
Which three DELETE statements execute successfully?
A) DELETE FROM orders WHERE order_total<1000;
B) DELETE * FROM orders WHERE order_total<1000;
C) DELETE orders WHERE order_total<1000;
D) DELETE FROM orders;
E) DELETE order_id FROM orders WHERE order_total<1000;
Answer：ACD
(解析：这个考的是语法题，属于低智商题目，因为定义外键的时候用了 DELETE CASCADE 选项，所以父表的行是可以删除。)
原文：https://blog.51cto.com/13854012/2459181