来自和列的MYSQL SELECT DISTINCT值以及来自另一个的对应值

Question

I have a column in a database which i use the below code to get the distinct values from that column

"SELECT DISTINCT category FROM galleryinfo"

I have another column with the path to the relevant image.

So my question is how do i get the unique/distinct values from category and it corresponding path from the other column.

Thanks in advance for any help.

id    path           category
1     img1           car
2     img2           car
3     img3           truck
4     img4           truck
5     img5           bike

The result i require would be

img1   car     
img3   truck   
img5   bike

Answer 1

You can use a GROUP BY query to reduce the result to one row per distinct category:

SELECT category, path FROM galleryinfo GROUP BY category

The problem with this is that it's arbitrary which path this query returns. In fact, in most SQL implementations, this is an illegal query and results in an error. MySQL is more lenient, but it will return an arbitrary path from those matching the category (in practice, it chooses the path from the first row with respect to physical storage, but this is not documented or guaranteed).

You can choose either the MIN(path) or MAX(path) , or concatenate all paths per category together into one string with GROUP_CONCAT(path) , but that's about it.