php - Mysql data selecting with particular price range, product limit, and other filtering -


i have database table product example:

id  name     price category 1   pen      70      1 2   banana   50      1 3   potato   10      1 5   apple    20      1 6   guaba    30      1 7   papa     30      2 8   salt     80      2 9   butter   25      2 10  cheese   10      2 11  burger   20      2 12  mashala  25      2 13  chuijal  40      3 14  icecream 20      3 15  chocolate 35     3

i want product mysql database based on price range, product limit, , category based. example: when want 4 products category=1 on cumulative price of 4 products 100 or near 100, show 4 product category 1 , price of 4 products 100 in total. possible output:

id  name     price category 1   pen      10      1 2   banana   50      1 3   potato   10      1 5   apple    20      1 ============================             =90 (near 100)

again when want 3 products of category 1, prices cumulative 100, show 3 product category 1 prices cumulative 100 or near 100.

possible out put:

  id  name     price category     1   pen      70      1     3   potato   10      1     5   apple    20      1 ============================                 =100

thus way, want result form different category different price range , product limit. data example, actual data many items , many different prices , other filterings category filtering.

i appreciate experts!

you can write separate query each problem products:

select p1.id, p2.id, p3.id, p4.id products p1 join      products p2      on p1.id < p2.id , p1.category = 1 , p2.category = 1 join      products p3      on p2.id < p3.id , p3.category = 1 join      products p4      on p3.id < p4.id , p3.category = 1  order abs(100 - (p1.price + p2.price + p3.price + p4.price)) limit 1;

this doing brute force search, generating combinations of products. should work find on data, if have thousands of rows, might take while.

optimizing type of search not problem can solve wholly within database. can review wikipedia page on knapsack problem better understand it. section on computational complexity explains why brute force approach best known approach optimization (in case don't understand computational complexity).


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