更改主键

本文介绍了更改主键的处理方法，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

我在Oracle中有一个表，该表具有以下架构:

I have a table in Oracle which has following Schema:

City_ID Name State Country BuildTime Time

当我声明表时，我的主键既是City_ID又是BuildTime，但是现在我想将主键更改为三列:

When i declared the table my primary key was both City_ID and the BuildTime but now I want to change the primary key to three columns:

City_ID BuildTime Time

如何更改主键?

推荐答案

假设您的表名是city，而现有的主键是pk_city，则您应该能够执行以下操作:

Assuming that your table name is city and your existing Primary Key is pk_city, you should be able to do the following:

ALTER TABLE city DROP CONSTRAINT pk_city; ALTER TABLE city ADD CONSTRAINT pk_city PRIMARY KEY (city_id, buildtime, time);

确保没有time为NULL的记录，否则您将无法重新创建约束.

Make sure that there are no records where time is NULL, otherwise you won't be able to re-create the constraint.