wordpress - $wpdb query not working in plugin -

i'm trying reviews plugin in wordpress, , 1 of thing client asked me user should able rate 1 product every 24 horas, have establish limit between rates.

and made function check if limit reached:

function isallowedtorate(){          global $wpdb;         $currentdate = date('y-m-d');         $userid = get_current_user_id();         $table_name = $wpdb->prefix .'esvn_reviews';         $isallowed = $wpdb->get_results(                  "                 select user_id, fecha_calificacion                  {$table_name}                 user_id = {$userid}                      , review_date = {$currentdate}                 "             );          if( count( $isallowed > 0 ) ){              return false;          }else{              return true;         }      } 

but every time try run it, returns false, error i'm getting wordpress this:

 <div id='error'>             <p class='wpdberror'><strong>wordpress database error:</strong> []<br />             <code>             select user_id, fecha_calificacion              wp_esvn_reviews             user_id = 6                  , fecha_calificacion = 2015-10-30             </code></p>             </div> 

if take same sql , run directly database, works charm, keep getting error wordpress , function returns false.

you need wrap date in single quotes.

    $isallowed = $wpdb->get_results(              "             select user_id, fecha_calificacion              {$table_name}             user_id = {$userid}                  , review_date = '{$currentdate}'             "         ); 

alternatively use $wpdb->prepare(), consider better form.

$sql = <<<sql     select user_id, fecha_calificacion      {$table_name}             user_id = %d -- formatted (d)igit       , review_date = %s -- formatted (s)tring sql; $isallowed = $wpdb->get_results($wpdb->prepare($sql, $userid, $currentdate));