php - check if row exists with mysql -

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i need checking if row exists. getting "email no longer exists publisher@example.com".

is there better way check if row exists mysqli?

if (count($_post)) {     $email = $dbl->real_escape_string(trim(strip_tags($_post['email'])));     $passwd = $dbl->real_escape_string(trim(strip_tags($_post['passwd'])));      $query = "select `email` `tbluser` `email` = '$email'";     $result = mysqli_query($dbl,$query);      if(is_resource($result) && mysqli_num_rows($result) == 1 ){             $row = mysqli_fetch_assoc($result);             echo $email . " email exists " .  $row["email"] . "\n";     }     else{             echo "email no longer exists" . $email . "\n";     }    }

the following tried, tested , proven methods check if row exists.

(some of use myself, or have used in past).

edit: made previous error in syntax used mysqli_query() twice. please consult revision(s).

i.e.:

if (!mysqli_query($con,$query)) should have read if (!$query).

  • i apologize overlooking mistake.

side note: both '".$var."' , '$var' same thing. can use either one, both valid syntax.

here 2 edited queries:

$query = mysqli_query($con, "select * emails email='".$email."'");      if (!$query)     {         die('error: ' . mysqli_error($con));     }  if(mysqli_num_rows($query) > 0){      echo "email exists";  }else{      //  }

and in case:

$query = mysqli_query($dbl, "select * `tbluser` email='".$email."'");      if (!$query)     {         die('error: ' . mysqli_error($dbl));     }  if(mysqli_num_rows($query) > 0){      echo "email exists";  }else{      //  }

you can use mysqli_ prepared statement method:

$query = "select `email` `tbluser` email=?";  if ($stmt = $dbl->prepare($query)){          $stmt->bind_param("s", $email);          if($stmt->execute()){             $stmt->store_result();              $email_check= "";                      $stmt->bind_result($email_check);             $stmt->fetch();              if ($stmt->num_rows == 1){              echo "that email exists.";             exit;              }         }     }

or pdo method prepared statement:

<?php $email = $_post['email'];  $mysql_hostname = 'xxx'; $mysql_username = 'xxx'; $mysql_password = 'xxx'; $mysql_dbname = 'xxx';  try { $conn= new pdo("mysql:host=$mysql_hostname;dbname=$mysql_dbname", $mysql_username, $mysql_password);       $conn->setattribute(pdo::attr_errmode, pdo::errmode_exception); } catch (pdoexception $e) {      exit( $e->getmessage() ); }  // assuming named submit button if(isset($_post['submit']))     {          try {             $stmt = $conn->prepare('select `email` `tbluser` email = ?');             $stmt->bindparam(1, $_post['email']);              $stmt->execute();             while($row = $stmt->fetch(pdo::fetch_assoc)) {              }         }         catch(pdoexception $e) {             echo 'error: ' . $e->getmessage();         }      if($stmt->rowcount() > 0){         echo "the record exists!";     } else {         echo "the record non-existant.";     }       } ?>
  • prepared statements best used protect against sql injection.

n.b.:

when dealing forms , post arrays used/outlined above, make sure post arrays contain values, post method used form , matching named attributes inputs.

  • fyi: forms default method if not explicity instructed.

note: <input type = "text" name = "var"> - $_post['var'] match. $_post['var'] no match.

  • post arrays case-sensitive.

consult:

error checking references:

please note mysql apis not intermix, in case may visiting q&a , you're using mysql_ connect (and querying with).

  • you must use same 1 connecting querying.

consult following this:

if using mysql_ api , have no choice work it, consult following q&a on stack:

the mysql_* functions deprecated , removed future php releases.

  • it's time step 21st century.

you can add unique constraint (a) row(s).

references:


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