Undefined Variables Error - PHP -

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i'm declaring 2 error. i'm thinking of isset don't know how use it. it's been 3 weeks self-studying php , i'm not yet.

 $searchq = $_post['lname'];  $searchw = $_post['fname']; 

this errors:

undefined variable: searchq  undefined variable: searchw 

i appreciate help.

$per_page = 20;                  $pages_query = mysql_query("select count(fname) sheet1");                 $pages = ceil(mysql_result($pages_query, 0) / $per_page);                  $page = (isset($_get['page'])) ? (int)$_get['page'] : 1;                 $start = ($page - 1) * $per_page;                  if( (isset($_post['fname'])) && (isset($_post['lname'])) ){                     ($searchq = $_post['lname']);                     ($searchw = $_post['fname']);                  }                 $query = mysql_query("select * sheet1 lname '%$searchq%' , fname '%$searchw%' limit $start, $per_page");                     while($query_row = mysql_fetch_assoc($query)){                         echo '<p>', $query_row['fname'] . ' ' . $query_row['lname'] ,'</p>';                     }                  if($pages >= 1 && $pages <= $pages){                     for($x=1; $x<=$pages; $x++){                         echo ($x == $page) ? '<strong><a href="?page='.$x.'">'.$x.'</a></strong> ' :  '<a href="?page='.$x.'">'.$x.'</a> ';                     }                  } 

this whole content of code. i'm making search box every time enter in empty value got error , displays records in database.

your problem before query. need ensure variables exist before use them.

[..]             if ( isset( $searchw ) && isset( $searchq ) ) {                 $query = mysql_query("select * sheet1 lname '%$searchq%' , fname '%$searchw%' limit $start, $per_page");                     while($query_row = mysql_fetch_assoc($query)){                         echo '<p>', $query_row['fname'] . ' ' . $query_row['lname'] ,'</p>';                     }             } else {                  // variables not set...                  echo "you performed empty search.";             } [..]