Question

I’m trying to sort data by different fields ascending and descending. But I have different mysql pdo statements for the 4 fields I have (8 queries total):

$stmt1 = $po->prepare("SELECT * FROM tabname WHERE categ=:categ ORDER BY field1 DESC");
$stmt2 = $po->prepare("SELECT * FROM tabname WHERE categ=:categ ORDER BY field1 ASC");
$stmt3 = $po->prepare("SELECT * FROM tabname WHERE categ=:categ ORDER BY field2 DESC");
$stmt4 = $po->prepare("SELECT * FROM tabname WHERE categ=:categ ORDER BY field3 ASC");
$stmt5 = $po->prepare("SELECT * FROM tabname WHERE categ=:categ ORDER BY field3 DESC");
$stmt6 = $po->prepare("SELECT * FROM tabname WHERE categ=:categ ORDER BY field3 ASC");
$stmt7 = $po->prepare("SELECT * FROM tabname WHERE categ=:categ ORDER BY field4 DESC");
$stmt8 = $po->prepare("SELECT * FROM tabname WHERE categ=:categ ORDER BY field4 ASC");

Based on input, I pick the right statement and bind and execute it.

if ($sortcode == 1){ 
   $stmt1->bindParam(':categ', $categ, PDO::PARAM_STR);
   $stmt1->execute();
   $fetched = $stmt1->fetchAll(PDO::FETCH_ASSOC);
} else if ($sortcode == 2){
   $stmt2->bindParam(':categ', $categ, PDO::PARAM_STR);
   $stmt2->execute();
   $fetched = $stmt2->fetchAll(PDO::FETCH_ASSOC);
} else if ($sortcode == 3){
   $stmt3->bindParam(':categ', $categ, PDO::PARAM_STR);
   $stmt3->execute();
   $fetched = $stmt3->fetchAll(PDO::FETCH_ASSOC);
}
//repeat the block 5 more times, for a total of 8

This doesn’t look right at all. Since the select statements only differ int he name of the field and the desc/asc, is there a better way to get the $sortcode and compact the code that follows?

I guess I could state the question more specifically as: is there a way I could have a single statement/single pdo statement that binds the field name and asc/decs dynamically?

Answer 1

Use associative arrays to hold the prepared statements.

Your input is a column and a sorting method, right? So prepare the queries by:

$columns = array("field1", "field2", "field3", "field4");
$orders = array("asc", "desc");
$queries = array();
foreach($columns as $col) {
  $queries[$column] = array();
  foreach ($orders as $order) {
     $queries[$column][$order] = $po->prepare("SELECT * FROM tabname WHERE categ=:categ ORDER BY $column $order");
  }
}

Now, to look up the correct query, you don’t need some synthetic code — you just look it up by column and order directly.

To look up a query, instead of having your users input a number from 1-8, have them input a column and an order. Imagine that the column is in the variable $col and the order is in $ord. Just say $queries[$col][$ord].

If for some reason you have to use the number (why?), then you need a slightly different strategy. In that case, you store the queries by that number.

$columns = array("field1", "field2", "field3", "field4");
$orders = array("asc", "desc");
$queries = array();
$i = 0;
foreach($columns as $col) {
  foreach ($orders as $order) {
     $i = $i + 1;
     $queries[$i] = $po->prepare("SELECT * FROM tabname WHERE categ=:categ ORDER BY $column $order");
  }
}

In other words, you ought to be storing queries according to how you plan to look them up.