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分类: Oracle

2019-12-17 09:58:46

choose three

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。)

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