从数组和变量过滤时，PHP mysql查询问题

Question

On my webpage (html, php), I'm trying to get it such that users may select multiple checkboxes, each checkbox effectively filters what results the users see. Info is pulled from the database (MySQL) based on the values in different columns. As shown below, one column is Joint_1, another column is Position.

Effective code that WORKS for filtering (very static, not practical to use obviously) is this:

$sql = "SELECT * FROM `Table_Name` WHERE (Joint_1=\'region1\'  OR  
                                          Joint_1=\'region2\'  OR  
                                          Joint_1=\'region3\' OR
                                          Joint_1=\'region4\') AND
                                         (Position=\'position1\' OR
                                          Position=\'position2\' OR
                                          Position=\'position3\')";
$result = $conn->query($sql);

if($result->num_rows > 0) {
   while($row = $result->fetch_assoc()) {
      echo $row["Common_Name1"] . "<br>";
   }
} else {
  echo "0 results";
  }

Below code is attempts at above code, but using arrays, which does NOT work.

$regions = 
array('region1', 'region2', 'region3', 'region4');
$position = array('position1', 'position2', 'position3');

$sql = "SELECT * FROM `Table_Name` WHERE (Joint_1=\'. $regions[0] .\'  OR  
                                          Joint_1=\'. $regions[1] .\'  OR  
                                          Joint_1=\'. $regions[2] .\' OR
                                          Joint_1=\'. $regions[3] .\') AND
                                         (Position=\'. $position[0] .\' OR
                          Position=\'. $position[0] .\' OR
                      Position=\'. $position[0] .\')"; 

Above code provides results of '0 results.'

I've attempted to perform this numerous times, with additional NON-FUNCTIONAL CODE also below (below attempting to filter based on only 1 column as I have obviously not mastered the code to approach filtering based on 2 columns).

$sqlregion = array();
foreach ($_POST['region'] as $reg) {
   $sqlreg[] = "'" . mysql_real_escape_string($reg) . "'";   
}
$sql = "SELECT * FROM 'Exercises' WHERE Joint_1 IN (" . implode(",", 
$sqlreg) . ");";

$result=$conn->query($sql);

if($result->num_rows > 0) {
   while($row = $result->fetch_assoc()) {
     echo $row["Common_Name1"] . "<br>";
   } 
}

Any help is appreciated! Thanks.

Answer 1

You can construct this query from arrays, you can use the IN clause in mysql to specify multiple OR values

$regions = array('region1', 'region2', 'region3', 'region4');
$position = array('position1', 'position2', 'position3');
$regions = implode(",", $regions); // Converts array to string with comma as a separator
$position = implode(",", $position);
$sql = "SELECT * FROM `Table_Name` WHERE Joint_1 IN ($regions) AND Position IN ($position)";
echo $sql;

This gives you a query like this

SELECT * FROM Table_Name WHERE Joint_1 IN (region1,region2,region3,region4) AND Position IN (position1,position2,position3)

add in your own LIMIT GROUP BY or ORDER BY parameters to suit your needs