Using MYSQLI in seperate / distinct PHP functions - php

Question

I'm transitioning from MYSQL to MYSQLI and I am in need of assistance with putting MYSQLI into separate / distinct functions.
From all the "tutorials" i have located on the web, they all have everyrything in one big long code, and not distinct / separate functions that my main scripts can call.
Eg :-
Connect to MYSQLI
Do SELECT
Exit MYSQLI
what i'm after is :-
MYSQLI.PHP
<?
function connect_mysqli()
{
$con=mysqli_connect("localhost","wrong_user","my_password","my_db");
// Check connection
if (!$con)
{
die("Connection error: " . mysqli_connect_errno();
}
// Return the connection back to where i called it ??
}
function do_query ($sql)
{
$row = $con->query("$sql")->fetch_array();
return $row;
}
function close_mysqli()
{
$mysqli->close();
}
?>
in my script i want to call :-
another.php
<?
include_once("MYSQLI.PHP");
connect_mysqli();
....
do some SELECT
do some UPDATE
close_mysqli();
?>
So far, from the error codes I am receiving, the "connection" to mysqli is not being passed to/from my other script(s)
Has anyone got a working / tested example of mysqli using functions (not just half the code) - but a working example of simple SELECT
Once i get that far, i can do the rest.

Answer 1

fix your include file to
/**
* #return mysqli
*/
function connect_mysqli()
{
$con = mysqli_connect("localhost","wrong_user","my_password","my_db");
// Check connection
if (!$con)
{
die("Connection error: " . mysqli_connect_errno());
}
return $con;
}
function do_query ($con, $sql)
{
$row = $con->query("$sql");
if($row) {
return $row->fetch_array();
}
return null;
}
function close_mysqli($con)
{
$con->close();
}
now you can run a script like this
include_once("MYSQLI.PHP");
$connection = connect_mysqli();
if(null !== $connection) {
print_r(do_query($connection, "SELECT * FROM yourTable"));
close_mysqli($connection);
}
but for correct handling create a connection interface and a implementation for mysqli like this
interface myConnectionClass {
function connect();
....
}
and a mysqli implementation
class myMysqlIConnection implements myConnectionClass {
function connect() {
//do more... save connection etc...
return true; //sucess
}
}

Answer 2

Example Demos
Scroll down there are a lot of exmaples...
<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
/* check connection */
if ($mysqli->connect_errno) {
printf("Connect failed: %s\n", $mysqli->connect_error);
exit();
}
/* Create table doesn't return a resultset */
if ($mysqli->query("CREATE TEMPORARY TABLE myCity LIKE City") === TRUE) {
printf("Table myCity successfully created.\n");
}
/* Select queries return a resultset */
if ($result = $mysqli->query("SELECT Name FROM City LIMIT 10")) {
printf("Select returned %d rows.\n", $result->num_rows);
/* free result set */
$result->close();
}
/* If we have to retrieve large amount of data we use MYSQLI_USE_RESULT */
if ($result = $mysqli->query("SELECT * FROM City", MYSQLI_USE_RESULT)) {
/* Note, that we can't execute any functions which interact with the
server until result set was closed. All calls will return an
'out of sync' error */
if (!$mysqli->query("SET #a:='this will not work'")) {
printf("Error: %s\n", $mysqli->error);
}
$result->close();
}
$mysqli->close();
?>