PHP PDO is a MySQL handler which uses object orientation. As PDO executes queries with prepared statements it is (with correct usage) safer than MySQLi.

Below is the PHP PDO cheat sheet which goes through creating a connection, selecting, inserting, updating, deleting and more. View the GitHub Gist here.

<?php
//Create connection
$db = new PDO('mysql:host=localhost;dbname=DATABASENAME;charset=utf8mb4', 'USERNAME', 'PASSWORD');
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);//https://www.php.net/manual/en/pdo.setattribute.php

//Check connection status
echo $db->getAttribute(PDO::ATTR_CONNECTION_STATUS);

//SELECT with loop
$select = $db->prepare("SELECT `col`, `col2` FROM `table`");
$select->execute();
while ($row = $select->fetch(PDO::FETCH_ASSOC)) {
    $db_col = $row['col'];
    $db_col2 = $row['col2'];
    echo "$db_col $db_col2<br>";
}

//SELECT with WHERE one value
$uid = 1610;
$select = $db->prepare("SELECT `col`, `col2`, `col3` FROM `table` WHERE `uid` = :uid LIMIT 1;");
$select->execute(array(':uid' => $uid));
$row = $select->fetchAll(PDO::FETCH_ASSOC);
$col = $row[0]['col'];

//SELECT with WHERE shorter
$select = $db->prepare("SELECT `col`, `col2` FROM `table` WHERE `id` = :id;");
$row = $select->fetch($select->execute(array(':id' => $id)));

//fetch for one/first row fetachAll for many/all rows

//SELECT simple
$select = $db->prepare("SELECT `col`, `col2`, `col3` FROM `table`");
$select->execute();
$row = $select->fetch();
$db_col = $row['col'];
$db_col2 = $row['col2'];
$db_col3 = $row['col3'];

//SELECT with WHERE
$select = $db->prepare("SELECT `col`, `col2`, `col3` FROM `table` WHERE `id` = :id");
$select->execute(array(':id' => $value));
$row = $select->fetch();
$db_col = $row['col'];
$db_col2 = $row['col2'];

//Bind Param
$select = $db->prepare("SELECT `col` FROM `table` WHERE `id` = :id AND `first_name` = :fname");
$select->bindParam(':id', $id, PDO::PARAM_INT);//https://www.php.net/manual/en/pdo.constants.php
$select->bindParam(':fname', $first_name, PDO::PARAM_STR);
$select->execute();

//Count returned columns
$select = $db->prepare("SELECT `col` FROM `table` WHERE `col` = :id");
$select->execute(array(':id' => $id));
$column_count = $select->columnCount();//Column count

//Check if row exists
$select = $db->prepare("SELECT `col` FROM `table` WHERE `col` = :id");
$select->execute(array(':id' => $id));
$result = $select->fetchColumn();
if ($result > 0) {
    echo "Row has been found";
} else {
    echo "No row in DB";
}

//Get last inserted id
$id = $db->lastInsertId();

//INSERT
$insert = $db->prepare('INSERT INTO `table` (`col`, `col2`) VALUES (?, ?)');
$insert->execute(["$value", "$value2"]);

$insert = $db->prepare('INSERT INTO `table` (`col`, `col2`, `col3`, `col4`, `col5`, `col6`, `col7`, `col8`, `col9`, `col10`) 
VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)');
$insert->execute(["$value", "$value2", "$value3", "$value4", "$value5", "$value6", "$value7", "$value8", "$value9", "$value10"]);

$insert = $link->prepare('INSERT INTO `table` (`col`, `col2`, `col3`)
    VALUES (:avalue, :avalue2, :avalue3)');
$insert->execute([
    'avalue' => '1',
    'avalue2' => $value2,
    'avalue3' => $value3,
]);

//INSERT shorter form
$data = [];//an array
$db->beginTransaction();
$stmt = $db->prepare("INSERT IGNORE INTO `table` (`col`, `col2`, `col3`) VALUES (?,?,?)");
for ($i = 0; $i < count($data); $i++) {
    $stmt->execute($data[$i]);
}
$db->commit();

//UPDATE on WHERE
$update = $db->prepare("UPDATE `table` SET `col` = 1 WHERE `col2` = :the_value");
$update->execute(array(':the_value' => $value));

//UPDATE on WHERE 2
$update = $db->prepare("UPDATE `table` SET `col` = :update_to WHERE `col2` = :the_value");
$update->execute(array(':update_to' => $update_to, ':the_value' => $value));

//UPDATE
$update = $db->prepare("UPDATE `table` SET `col` = 1");
$update->execute();

//DELETE
$delete = $db->prepare("DELETE FROM `table` WHERE `col2` = :the_value");
$delete->execute(array(':the_value' => $value));