# UNION ALL

Let’s say we want to print `id cards`

for all the `students`

and the `books`

. Each id card for a student will just have his id, and each id card for a book will just contain its id. Now say we have to `print all the ids`

in a single result, under a single column.

This looks like a perfect use case for `UNION`

query. Go ahead and run the query below.

Notice that we have 34 records in the results. But we expect a total of ids of 25 students and 34 books. The ids for students range from 1 to 25, and for books, range from 1 to 34. The results of the above query are just 1 to 34. This goes on to explain that if there are records exactly matching from multiple queries in a `UNION`

, only one of them will be included in the final results. That’s another way of saying that the results of a `UNION`

are always `unique`

.

Then how do we solve our problem? We need all 25 student ids and all 34 book ids. In such cases, there is an extension to `UNION`

, called `UNION ALL`

. Run the query below:

Notice that by using `UNION ALL`

, we get all (25 + 34) results, as expected.