使用联接和匹配进行MySQL搜索

Question

I've got one table filled with information about companies (tblforetag) in Sweden, one table with provinces (tbllan) and one table with cities (tblstad). The cities are linked to the provinces with id numbers and the company table has a column for the city name (varchar).

How do I search for all the companies in one province?

I have fiddled around with joins but not got it to work. I've got this code right now that works but it will only search for company names and cities (in the company table):

$sql = "
    SELECT *, 
    MATCH(tblforetag.foretag) AGAINST(:keywords) AS kr
    FROM tblforetag
    WHERE MATCH(tblforetag.foretag) AGAINST(:keywords)
    ";
$sql .= $locisset ? "AND tblforetag.stad LIKE :location" : "";
$sql .= " LIMIT $offset, $rpp"; 
$query = $conn->Prepare($sql);
$query->BindValue(':keywords', $keywords);
if($locisset) $query->BindValue(':location', "%$location%");
$query->Execute();

Answer 1

I do not know your table structure but something along these lines shoulod do the trick:

SELECT FROM companies 
LEFT JOIN cities ON (companies.city_id = cities.id)
LEFT JOIN regions ON (cities.region_id = regions.id)
WHERE region.name = 'your region'

This would give you the companies in that particular region.

Answer 2

I think it would be better the city_name column in companies table to city_id.

SELECT a.*, p.provincename
FROM   companies a, cities c, provinces p
WHERE a.city_name = c.city_name
AND      c.city_id = p.city_id
AND      p.province_id = 5 // give your province id here