Space.As's Blog

if($category || $make || $model || $condition) {
  // build query string
  $query = "SELECT * FROM $dbvin WHERE";
  if($category) { $query .= " category='$category' AND"; }
  if($make) { $query .= " make='$make' AND"; }
  if($model) { $query .= " model LIKE '%$model%' AND"; }
  if($condition) { $query .= " condition='$condition'"; }
  // trim extra AND if neccessary
  if(substr($query, strlen($query)-4, 4) == ' AND') {  $query = substr($query, 0, strlen($query)-4); }
} else {
  $query = "SELECT * FROM $dbvin";
}

.= 最基础的东西,我开始写的 多条件查询 写的好复杂, 看到这个写法后 才发觉 .= 这个运算符号的用处.