CRUD using prepare statement not working. - php

Question

Database connecting is working. The SELECT AND UPDATE FUNCTION in the class is not working at all.It is not even showing errors to help me sort out the problem. I am trying to learn how to use the prepare ,bind-param and execute statement. Please can someone help look at the codes and advise what may be wrong with it. Just spent loads of hours on this and just cant figure where the problems is. please can some help me.I am a novice and writing my very first codes . Many thanks in advance
<?php class connect_dbase{
public $mysqli;
public function connection($host="localhost",$user="root",$password="london",$db_name="users")
{
$this->mysqli=new mysqli($host,$user,$password,$db_name);
if ($this->mysqli->connect_error) {
die('Connect Error: ' . $this->mysqli->connect_error);
}
else{
echo " Database connection successful";
}
}
public function display_all($id){
if($stmt = $this->mysqli->prepare("SELECT * FROM user WHERE id =?")){
/* bind parameters for markers */
$stmt->bind_param('i',$id);
/* execute query */
$stmt->execute();
if($stmt->num_row() >0){
echo 'Total results: ' . $resultrol->num_rows;
$result = $stmt->get_result();
while ($row = $result->fetch_assoc()) {
echo $row['name'];
echo $row['email'];
echo $row['address'];}
}
else { echo "no result found";}
}
else
{
echo "cant prepare result";
}
}
public function update_post($name, $address,$email,$mob,$id)
{
$up="UPDATE user SET name=?, address =?,email=?,mobile=? WHERE id =?";
if($stmt=$mysqli->prepare($up))
{
$stmt->bind_param("sssii", $name, $address,$email,$mob,$id);
if($stmt->excute()) {
echo " post updated";
header('location:index.php');
}
else
{
echo "post not executed";
}
}else{ echo " cannot prepare statement";}
}
}
$connect_dbase=new connect_dbase();
$connect_dbase->connection();
$connect_dbase->display_all(2);
$connect_dbase-> update_post("john","kkkkk","kkk#yahoo.com",98765,2);
// These 2 functions- $connect_dbase->display_all(2); and
$connect_dbase-> update_post("john","kkkkk","kkk#yahoo.com",98765,2); are not working when called from the class above .
?>

Answer 1

I agree with #MikeBrant's comments. You should make the connection happen in the constructor if you want to be assured that the connection is successful before you try to call it.
Here's another tip:
if($stmt->num_row() >0){
Note that num_rows() doesn't return anything useful until after the client has fetched the rows. So calling it right after execute() is pretty much guaranteed to make it return the wrong number.
You need to use mysqli::store_result() to transfer the result set from the server to the client, and then num_rows() will work. But be careful if the result set is very large, it could use too much memory.

Answer 2

Taking into account the input from Mike and Bill I have modified your code to make it functional. It could use some more work but it should give you a starting point at the very least. I created a test database with three fields, id, name and email but you should be able to plug in your own database and fields and have it still work.
<?php
class connect_dbase {
public $mysqli;
public function connection($host="localhost",$user="root",$password="",$db_name="test")
{
$this->mysqli=new mysqli($host,$user,$password,$db_name);
if ($this->mysqli->connect_error) {
die('Connect Error: ' . $this->mysqli->connect_error);
} else {
// return a true value here if successful, that way you can check
// if your connection was established
return true;
}
}
public function display_all($id){
if($stmt = $this->mysqli->prepare("SELECT * FROM test WHERE id =?")) {
// some minor changes to the bind and execute statments. I
// wrapped them in an if just to make sure there were no errors
// if i had more time i might make these more elegant rather than just
// echoing them out
/* bind parameters for markers */
if(!($stmt->bind_param('i',$id))) {
echo $stmt->error;
}
/* execute query */
if(!($stmt->execute())) {
echo $stmt->error;
}
// You could also bind the results to specific variables here and return those
//$stmt->bind_result($id,$name,$email);
//$stmt->fetch();
//$result = $name;
//assign the results to a variable and then return that variable
//rather than processing the results here
$result = $stmt->get_result();
return $result;
} else {
// if an error occurs return the error, once again another place for
// improvement but at the very least will show you an error
echo $this->mysqli->error;
}
}
public function update_post($name, $email, $id)
{
$up="UPDATE test SET name=?, email=? WHERE id =?";
// originally had $mysqli->prepare($up), fixed syntax
if($stmt = $this->mysqli->prepare($up))
{
//$stmt->bind_param("sssii", $name, $address,$email,$mob,$id);
$stmt->bind_param("ssi", $name, $email,$id);
// execute was spelled wrong
if($stmt->execute()) {
return true;
} else {
return $stmt->error;
//return false;
}
} else {
return false;
}
}
}
// set up database connection
$connect_dbase = new connect_dbase();
if($connect_dbase->connection()) {
// if connection was successful, call display_all
// and assign the results to $result
$result = $connect_dbase->display_all(2);
// you could do a foreach here also but since there
// was only one result i just echoed the values
while($row = $result->fetch_array()) {
echo $row['id'] . "<br/>";
echo $row['name'] . "<br/>";
echo $row['email'] . "<br/>";
}
// then call update_post
$update_result = $connect_dbase->update_post("asdf","asdf#yahoo.com",2);
// show a message if the update_post was successful
if($update_result) {
echo "Update successful";
}
}
?>
I commented the areas I switched around so you have an idea of what I did.