Ruby-on-rails 如何在rails中的两列上实现唯一索引
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时间：2020-09-02 23:35:40 来源:igfitidea点击:
How to implement a unique index on two columns in rails
提问by Markus
I have a table and I'm trying to add a unique index on two columns. Those columns are also indexed. So my question is if I just can remove the indexes who were just for one column or if I have to use all three indexes:
我有一个表，我正在尝试在两列上添加一个唯一索引。这些列也被索引。所以我的问题是我是否可以删除仅用于一列的索引，或者我是否必须使用所有三个索引：
add_index "subscriptions", ["user_id"]
add_index "subscriptions", ["content_id"]
add_index "subscriptions", ["user_id"], ["content_id"], :unique => true
回答by shingara
add_index :subscriptions, [:user_id, :content_id], unique: true
