Question

I am trying to execute multiple sql statements in yii , this is to reduce round trips to the server . This is for a field called niche specialization . A maximum of three enteries are allowed for a user , however the field is optional . This is the code :

$sql = " Delete from cur_niche 
         where userid =:id ; " ;
$var2 = array_filter($object->nspecial) ;
  if(!empty($var2))                 
                    {    $str = ""  ; 
                         $i = 0 ; 
                         foreach($var2 as $n) 
                         {   if($i==0)
                         $str.= "(:id,:n".$i.")" ;
                         else 
                         $str.= ", (:id,:n".$i.")" ; 
                         $i++ ;  
                         }
        $sql .= "Insert into cur_niche (userid,nspecial) Values ".$str." ; " ;
                    }
$command = Yii::app()->db->createCommand($sql)  ;
 $command->bindParam(":id",$id,PDO::PARAM_STR) ;
  if(!empty($var2))                     
    {     $i = 0 ;
         foreach($var2 as $n) 
            { 
             $str = ":n".$i ; 

            $command->bindParam($str,$n,PDO::PARAM_STR) ;
              $i++ ; 
                }
        }   
$result = $command->execute() && $result ; 

I have tried dumping all my variables , the sql statement is formed correctly , the $object has the correct data from the form , In the binding the $str is working fine .
However I am facing the following issue :
1) If there is only one entry in the niche spcialization array($object->nspecial) , the entry is working fine .
2) However if more than one field is filled , it fails to execute the insert , this is because the userid and nspecial fields form a composite primary key .

Doesnt the composite primary key depend on both values forming a unique combination (assuming that the user enters unique values in various fields) ?
If I remove the primary key constraint it just duplicates the value of one field with two rows in the db .What am I doing wrong here ?

Answer 1

Found the bug . For the ‘foreach’ loops I should be binding by value not by parameter , since it references to the most recent value of the parameter , thus duplicating values .