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2207/MySQL数据库操作综合练习题答案.md

@@ -33,5 +33,17 @@ ALTER TABLE customers_info DROP c_city;
 **2**
 
 ```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;
 ```