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Number of bind variables doesn't match number of fields in prepared statement 

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<?php
$mysqli = new mysqli("localhost","root","123456", "gfgd",3308);

/* check connection */
if (mysqli_connect_errno()) {
  printf("Connect failed: %s\n", mysqli_connect_error());
  exit();
}

$admin1 = "admin";

/* create a prepared statement */
if ($stmt = $mysqli->prepare("SELECT * from admin a WHERE a.admin_no=?"))
{

  /* bind parameters for markers */
  $stmt->bind_param("s", $admin1);

  /* execute query */
  $stmt->execute();

  /* bind result variables */
  $stmt->bind_result($district);

  echo $district;
  /* fetch value */
  //$stmt->fetch();


  /* close statement */
  $stmt->close();
}

/* close connection */
$mysqli->close();
?> 



?>

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$stmt->bind_param("s", $admin1);
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