Question

I have two tables:

table1:

ID | user | info
------------------
1    1      data1
2    1      data2
3    2      data3

table2:

table1_id | array_info
------------------------
1             a  
1             b
2             a
3             d
3             g
3             m

How can I efficiently return the rows associated with a user such that I get info and an array of that ID’s associated array_info?

For instance, a query like "select ID, info from table1 where user = 1" but would also return [a,b] from table2 so that the result would be something like [1, data1, [a, b]] with the first row and [2, data2, [a]] with the second row. Similarly, "…where user = 2" should return something like [3, data3, [d, g, m]]. I don’t think MySQL returns things quite like this, but perhaps PHP can smooth over the input of a left join? It seems wasteful to replicate all the data in info if MySQL returns a separate row for each array_info, but I’m not sure there’s another way.

Answer 1

You could use a GROUP_CONCAT with a JOIN and then when you iterate over the results, use explode() to convert the concatenated string to an array.