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smallkun 2025-03-14 08:53:36 +08:00
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2207/MySQL数据库操作综合练习题答案.md
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@ -33,5 +33,17 @@ ALTER TABLE customers_info DROP c_city;
**2** **2**
```sql ```sql
#(1)创建表时 添加外键约束并指定外键约束名称
CREATE TABLE orders(
o_num INT(11) PRIMARY KEY AUTO_INCREMENT,
o_date DATE,
c_id INT(11),
CONSTRAINT fk_cid FOREIGN KEY(c_id) REFERENCES customers_info(c_num)
);
#(2)
#删除指定外键
ALTER TABLE orders DROP FOREIGN KEY orders_ibfk_1;
#删除指定表
DROP TABLE orders;
``` ```