How do I set ORDER BY params using prepared PDO statement?

Question

I\'m having problems using params in the ORDER BY section of my SQL. It doesn\'t issue any warnings, but prints out nothing.

$order = \'column         


        

Answer 1

I don't think you can get ASC/DESC as part of the prepared statement, but the column you can if you list them all in the sql query like so:

// Validate between 2 possible values:
$sortDir = isset($_GET['sortDir']) && $_GET['sortDir'] === 'ASC' ? 'ASC' : 'DESC';
$sql = "
...
     order 
        by 
           case :orderByCol
               when 'email' then email
               when 'age' then age
               else surname
           end
           $sortDir
";
$stmt = $db->prepare($sql);
$stmt->bindParam(':orderByCol', $someColumn);
$stmt->execute();

Since ASC/DESC is only two possible values, you can easily validate and select between them as hardcoded values using php code.

You could also make use of the ELT(FIELD(,,,,,),,,,,) functions for this, but then ordering will always be done as a string, even if the column is a numeric data type that should be sorted using numeric semantics / collation.