Insert data into a table so that its primary key is combined from 2 columns

Question

I am combining these columns as a primary key.

room_no, type 

When I insert new data, for example, 0001 01 .

And then I insert 0001 02 .

It's impossible. He said a duplicate primary key. Why is it duplicated, although I define 2 columns as the primary key.

Answer 1

This is the same as the compsite key.

You can read this article: - http://www.techrepublic.com/article/the-great-primary-key-debate/1045050

Answer 2

Just a thought:

• Have you defined specific indexes on them?
• Have you identified each key individually as unique?