ALTER TABLE 添加复合主键 [英] ALTER TABLE to add a composite primary key
本文介绍了ALTER TABLE 添加复合主键的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我有一个名为 provider 的表.我有三列名为person、place、thing.可以有重复的人、重复的地点和重复的事物，但永远不可能有重复的人地物组合.
I have a table called provider. I have three columns called person, place, thing. There can be duplicate persons, duplicate places, and duplicate things, but there can never be a dupicate person-place-thing combination.
如何使用这三列在 MySQL 中为该表添加复合主键?
How would I ALTER TABLE to add a composite primary key for this table in MySQL with the these three columns?
推荐答案
ALTER TABLE provider ADD PRIMARY KEY(person,place,thing);
如果主键已经存在，那么你想这样做
If a primary key already exists then you want to do this
ALTER TABLE provider DROP PRIMARY KEY, ADD PRIMARY KEY(person, place, thing);
这篇关于ALTER TABLE 添加复合主键的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
查看全文
