php - function to check if data is on the database -

i create function find firstname , lastname in database want if data exist want output, error message

my question how create function check if data exist?

this function find data of firstname , lastname.

function find_student_by_firstname($firstname){   global $con;    $safe_firstname = prep($firstname);    $sql  = "select * ";   $sql .= "from studeprofile ";   $sql .= "where firstname = '{$safe_firstname}' ";   $sql .= "limit 1";   $student_set = mysqli_query($con, $sql);   confirm_query($student_set);   if($student = mysqli_fetch_assoc($student_set)){     return $student;   } else {     return null;   } }  function find_student_by_lastname($lastname){   global $con;    $safe_lastname = prep($lastname);    $sql  = "select * ";   $sql .= "from studeprofile ";   $sql .= "where lastname = '{$safe_lastname}' ";   $sql .= "limit 1";   $student_set = mysqli_query($con, $sql);   confirm_query($student_set);   if($student = mysqli_fetch_assoc($student_set)){     return $student;   } else {     return null;   } } 

this current function check if data exist.

function match_fistname_lastname($lastname, $firstname){   $student_firstname = find_student_by_firstname($lastname);   if($student_firstname){     find_student_by_lastname($lastname);   } else {     return false;   } } 

if mean "data exist" person in database matches firstname , lastname, don't have execute 2 queries. use and in mysql this:

function find_student($firstname, $lastname){   global $con;    $safe_firstname = prep($firstname);   $safe_lastname = prep($lastname);    $sql  = "select * ";   $sql .= "from studeprofile ";   $sql .= "where firstname = '{$safe_firstname}' , lastname = '{$safe_lastname}' ";   $sql .= "limit 1";   $student_set = mysqli_query($con, $sql);   confirm_query($student_set);   if($student = mysqli_fetch_assoc($student_set)){     return $student;   } else {     return null;   } }