SELECT
<?php
// consulta básica 
$consulta = db_query("SELECT campos  FROM {tabla}  WHERE columna='%s' ORDER BY columna2 DESC LIMIT $num_limite ", "$valor");
while ($result=db_fetch_object($consulta)){
  $valor1 = $result->campos;
}
//si se sabe que el resultado es único, que no es un array basta con la siguiente consulta:
$consulta = db_fetch_object(db_query("SELECT campos  FROM {tabla}  WHERE columna='%s' ORDER BY columna2 DESC LIMIT $num_limite ", "$valor"));
 
// contar resultados de una consulta
$consulta = db_result(db_query("SELECT COUNT(*) FROM {tabla} WHERE columna='%s'", "$valor" ));
 
// INNER JOIN
$consulta = db_query('SELECT * FROM {tabla1} t1 INNER JOIN {tabla2} t2 ON t1.columna=t2.columna WHERE t1.columna2 = %d ', $valor);
while ($result=db_fetch_object($consulta)){
  $valor1 = $result->campo;
}
 
 
DELETE
 
db_query("DELETE FROM {tabla} WHERE columna = '%s' " , $valor);
?>