Building dynamic sql statement in PHP

Question

i have that part of code and want to build a dynamic SQL Statement:

//Build IN Clause
$sql_IN="'".implode("','", $keywords)."'";

//Build COUNT Clause
//tbd

//Get Clicks from YOURLS LOG
$sql_get_clicks="
                    SELECT 
                        count(case when shorturl ='u0lg' then 1 end) u0lg, 
                        count(case when shorturl ='3a8h' then 1 end) 3a8h,  
                        count(case when shorturl ='abcd' then 1 end) abcd,  
                        DATE_FORMAT((click_time),'%d.%m.%Y') Datum
                    FROM 
                        `yourls_log` 
                    WHERE  
                         DATE(click_time) BETWEEN '20170102' AND '20170104' AND
                         shorturl IN (".$sql_IN.")
                    Group By Datum";

The variable $keywords is an array with keywords. The keywords are used in the IN Clause and must also be used within the "count case part". The quantity of keywords within the $keywords Array is variable. Any tips how i can build the count(case.. in an easy and good programming style?

Answer 1

You can iterate the $keywords array and put each value into a clause that you append after the SELECT and before the FROM etc.

$keywords = array("foo", "bar", "baz");
$inClause = "'".implode("','", $keywords)."'";
$sql = "SELECT ";
foreach($keywords as $key) {
  $sql.="count(case when shorturl = '".$key."' then 1 end) ".$key.", ";    
}
$sql=rtrim($sql, ", ")." ";
$sql.= "FROM `your_logs` 
  WHERE 
    DATE(click_time) BETWEEN '20170102' AND '20170104' AND
    shorturl IN (".$inClause.")
    Group By Datum";

Where a var_dump($sql); gives:

string(301) "SELECT count(case when shorturl = 'foo' then 1 end) foo, count(case when shorturl = 'bar' then 1 end) bar, count(case when shorturl = 'baz' then 1 end) baz, FROM your_logs WHERE DATE(click_time) BETWEEN '20170102' AND '20170104' AND shorturl IN ('foo','bar','baz') Group By Datum"

Regards programming style - you should most definitely look into prepared statements.