How to optimize mysql query for performance - php

Question

I have five tables with join. This query takes more than 5 sec to execute. I have four queries like the one below, so my PHP page takes more than 30 sec to load. I need to improve the performance. Could you please help me? I have struggled for a week. I added indexing.
MY QUERY
SELECT f.SortField , f.id
FROM tbl_store_brands AS sb
INNER JOIN tbl_products AS p
ON sb.categoryID = p.pkCategory AND sb.brandID = p.pkBrand
INNER JOIN ModelPrice AS mp ON (p.id = mp.product_id)
INNER JOIN Brand_Data AS bd ON bd.pkID = p.pkBrand+0
INNER JOIN tbl_filters AS f
ON (
p.pkID = f.pkID and
p.pkCategory = f.Category AND
p.cgSlug = 'bathroom-fixtures'
)
WHERE mp.Available = 1
GROUP BY f.SortField
ORDER BY if (
f.SortField = 'CAPACITY' OR
f.SortField = 'WIDTH' OR
f.SortField = 'HEIGHT' OR
f.SortField = 'DEPTH', 4, f.ValueDisplayOrder
) ASC
MY Query EXPLANATION

Answer 1

Few modification can be done, to improve you query performance.
1. Add index for ValueDisplayOrder, this will improve the sorting performance.
2. Avoid in query per functioning. Remove the "p.pkBrand+0", this add the execution process time. If possible remove the if clause from order by and do the ordering in your PHP code.
3. Move the "p.cgSlug = 'bathroom-fixtures'" code to on clause of product table join to narrow down the inner join result.
Your modified query will look like:
SELECT f.SortField , f.id
FROM tbl_store_brands AS sb
INNER JOIN tbl_products AS p
ON sb.categoryID = p.pkCategory AND sb.brandID = p.pkBrand AND p.cgSlug = 'bathroom-fixtures'
INNER JOIN ModelPrice AS mp ON (p.id = mp.product_id)
INNER JOIN Brand_Data AS bd ON bd.pkID = p.pkBrand
INNER JOIN tbl_filters AS f
ON (
p.pkID = f.pkID and
p.pkCategory = f.Category
)
WHERE mp.Available = 1
GROUP BY f.SortField
ORDER BY f.ValueDisplayOrder
ASC