MYSQL查询联接的问题

Question

i am performing search function i have contactgroup and language,

Here is mysql query:

$sql = "SELECT * FROM contact where isdeleted = 0  ";

      if ($language !="" && $language !="Empty" ){

                $language_exp = explode(',', $language);
     $sql .= " INNER JOIN contactlanguage ON contact.id = contactlanguage.contactid
INNER JOIN language ON contactlanguage.languageid = language.id AND language.language in ('".implode("', '", $language_exp)."')"; 

            }


    if ($contactgroup !="" && $contactgroup !="Empty" ){



    $contactgroup_exp = explode(',', $contactgroup);
    $sql .= " AND contactgroup in ('".implode("', '", $contactgroup_exp)."')";

    }

there are three cases first if i select only language the it will perform query like this

its not working

SELECT * FROM contact where isdeleted = 0 INNER JOIN contactlanguage ON contact.id = contactlanguage.contactid INNER JOIN language ON contactlanguage.languageid = language.id AND language.language in ('English', '') 

second if not selected language only selecting contactgroup its working,

SELECT * FROM contact where isdeleted = 0 AND contactgroup in ('Contactgroup1', '')

third case if i select both language and contactgroup its not working

SELECT * FROM contact where isdeleted = 0  INNER JOIN contactlanguage ON contact.id = contactlanguage.contactid INNER JOIN language ON contactlanguage.languageid = language.id AND language.language in ('English', '') AND contactgroup in ('Contactgroup1', '')

can anyone guide me how to perform the query for case 1 and case 3,thanks

Answer 1

The JOIN query is wrong and you will need to move the where condition after the JOIN statement something as

SELECT * FROM contact 
INNER JOIN contactlanguage ON contact.id = contactlanguage.contactid
INNER JOIN language ON contactlanguage.languageid = language.id
where 
isdeleted = 0   
AND language.language in ('English', '') 

Answer 2

The query's are wrong. You must first add the join statement and thene then where

SELECT * FROM contact INNER JOIN contactlanguage ON contact.id = ... where isdeleted = 0