Getting the most from a single MySQL query - php

Question

I have a website that lists apartments that are available for rent. I have a few different tables in my MySQL database. One table is for basic information about the Apartment building as a whole, including address, ammenities, photos, an ID (NID), etc.
Another table lists the units available for rent within each building. So each apartment building has multiple floorplans, with a few studios, a few 1 bedroom units, sometimes a few 2 bedroom units, etc.
Currently I query my 'unit' table and ask for all units in a given apartment building. My query looks something like SELECT * FROM node_unit WHERE nid='555'
This might return something like the following:
NID Name Rent SqFT Bedrooms Bathrooms
555 Unit 1 $500 620 0 1
555 Unit 2 $550 680 0 1
555 Unit 3 $600 820 1 1
555 Unit 4 $650 920 1 1
555 Unit 5 $700 1220 2 1
555 Unit 6 $800 1420 2 2
555 Unit 7 $900 1500 3 2
555 Unit 8 $1100 1620 3 3
etc, etc
What I am then doing in my PHP is using an accordian to group the 1 bedrooms together, the 2 bedrooms together, etc.
Not all apartments have 2 bedrooms units, some only have 1 bedroom units, so I need to know within my PHP code if I should print another accordian.
Currently I am using multiple hits to the database to determine if a given building has any 2 bedroom units, if so print another row. Does this building have any 3 bedroom units? If so print another row, but I would like to stop hitting my database so much.
Finally, here is my question:
How can I store the results from my first DB call and somehow parse thru the data and and determine if a given NID has studios, 1 beds, 2 beds, etc? (I just started learning PHP/MySQL recently)

Answer 1

I would suggest a query like this:
SELECT * FROM node_unit WHERE nid='555'
ORDER BY Bedrooms ASC, Bathrooms ASC, Rent ASC
This would return your records ordered by # of bedrooms, # bathrooms, and rent amount (in that order).
You could easily store this in multidimensional array when reading from database like this (assuming mysqli use with result set stored in $result, but concept is same for other DB connection libraries)
$room_array = array();
while ($row = mysqli_fetch_assoc($result)) {
$room_array[(int)$row['Bedrooms']][] = $row;
}
You now have a multidimensional array with number of bedrooms as first index. The array might look like this if you var_dump it:
Array (
[0] => Array (
[0] => Array (
'NID' => '555',
'Name' => 'Unit 1',
'Rent' => '$500',
'SqFt' => '620',
'Bedrooms' => '0',
'Bathrooms' => '1',
)
[1] => Array (
'NID' => '555',
'Name' => 'Unit 2',
'Rent' => '$550',
'SqFt' => '680',
'Bedrooms' => '0',
'Bathrooms' => '1',
)
)
[1] => Array (
[0] => Array (
'NID' => '555',
'Name' => 'Unit 3',
'Rent' => '$600',
'SqFt' => '820',
'Bedrooms' => '1',
'Bathrooms' => '1',
)
[1] => Array (
'NID' => '555',
'Name' => 'Unit 4',
'Rent' => '$650',
'SqFt' => '920',
'Bedrooms' => '1',
'Bathrooms' => '1',
)
[2] => Array (
...
)
[3] => Array (
...
)
)
This makes it really easy to iterate over the number of bedrooms values in an outer loop, which creates your accordions, and then iterate the individual rooms in an inner loop.
foreach ($room_array as $num_bedrooms => $rooms) {
// start accordion
foreach ($rooms as $room) {
// output room details
}
// end accordion
}
All this would only require the single query.
Also make sure you have indexes on bedrooms, bathrooms, rent (or whichever you use in the sort) as well as on nid since it is used as the filter.

Answer 2

Try this as your database query, it will generate a row for each building for each unit type it has. You could also use it as a subquery and join to the parent table to get any other details you need about the building in one shot.
select 'studio' as unit_type, nid from node_unit group by nid having count(case when bedrooms = 0 then 1 end) > 0
union all
select 'one bedroom' as unit_type, nid from node_unit group by nid having count(case when bedrooms = 1 then 1 end) > 0
union all
select 'two bedroom' as unit_type, nid from node_unit group by nid having count(case when bedrooms = 2 then 1 end) > 0
union all
select 'three bedroom' as unit_type, nid from node_unit group by nid having count(case when bedrooms = 3 then 1 end) > 0