Moving from MySQL to MySQLi - php

Question

Could somebody please point me in the right direction. I am in the process of making the transition from MySql to MySqli. Normally I would select from the database using th code below and it would allow me to easily use the column value as a working variable:
$SQLCommand = "SELECT * FROM table WHERE column1 = 'ok'";
$Data = mysql_query($SQLCommand);
$DataRow = mysql_fetch_assoc($Data);
$var1 = $DataRow["column1"];
$var2 = $DataRow["column2"];
$var3 = $DataRow["column3"];
$var4 = $DataRow["column4"];
I have researched how to do the MySql equivalent but I find theres a lot of different way using loops etc. Is there a like for like (for want of a better description) that does the same thing? Thanks in advance.

Answer 1

Instead of going with the flow, i care to suggest a PDO alternative
$db = new PDO($dsn, 'username','password');
//$dsn is the connection string to your database.
//See documentation for examples
//The next two rows are optional, but i personally suggest them to
//ease developing, debugging (the 1st) and fetching results (the 2nd)
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$db->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
$stmt = $db->prepare("SELECT * FROM table WHERE column1 = :c1");
$stmt->bindValue(':c1', 'ok'); //This example is trivial and not necessary
//but it gains relevance when the bound value
//is a variable
$rows = $stmt->fetchAll(); //if you expect a single row use fetch() instead
//do something with the results
You can read more about PDO here: PDO manual
The biggest PDO advantage is that it's independent of the actual database in use by your application. If, by chance, you want to change database in the future, for example SQLITE or PostgreSQL, the only* change you have to make is your $dsn connection string
[*] True only if you used standard SQL queries and nothing vendor-specific.

Answer 2

A direct conversion would be:
$Data = mysqli_query($connection, $SQLCommand);
$DataRow = mysqli_fetch_assoc($Data);
The difference, other than the i is that mysqli_query requires the connection as an argument (as do most mysqli_* functions).
MySQLi also has an object oriented style:
$Data = $connection->query($SQLCommand); // assuming you created the $connection object
$DataRow = $data->fetch_assoc();

Answer 3

They should be like
$mysqli = new mysqli("localhost", "my_user", "my_password", "my_db");
$SQLCommand = "SELECT * FROM table WHERE column1 = 'ok'";
$Data = $mysqli->query($SQLCommand);
$DataRow = $mysqli->fetch_assoc($Data);
Try this LINK

Answer 4

My suggestion is to use mysqli prepared statement whenever you are using user inputs to prevent SQL injection:
See below code uses object oriented approach and prepared statement
<?php
$mysqli = new mysqli("example.com", "user", "password", "database");
if ($mysqli->connect_errno) {
echo "Failed to connect to MySQL: (" . $mysqli->connect_errno . ") " . $mysqli->connect_error;
}
if (!$mysqli->query("DROP TABLE IF EXISTS test") ||
!$mysqli->query("CREATE TABLE test(id INT, label CHAR(1))") ||
!$mysqli->query("INSERT INTO test(id, label) VALUES (1, 'a')")) {
echo "Table creation failed: (" . $mysqli->errno . ") " . $mysqli->error;
}
/* Prepared statement, stage 1: prepare */
$stmt = $mysqli->prepare("SELECT id, label FROM test WHERE id = ?");
/* Prepared statement, stage 2: bind and execute */
$id = 1;
//note below "i" is for integer, "s" can be used for string
if (!$stmt->bind_param("i", $id)) {
echo "Binding parameters failed: (" . $stmt->errno . ") " . $stmt->error;
}
$stmt->execute();
$res = $stmt->get_result();
$row = $res->fetch_assoc();
printf("id = %s (%s)\n", $row['id'], gettype($row['id']));
printf("label = %s (%s)\n", $row['label'], gettype($row['label']));
?>