PDO Data Access Abstraction Layer

//pdo//data Access Abstraction Layer<?PHP//1. Operation of other databases//2. transaction function//3. Prevent SQL Injection Attack//Build PDO object//$dsn = "mysql:dbname=mydb;host=localhost";//Data source//$pdo = new PDO ($DSN, " Root "," 123 ");//write SQL statement//$sql =" SELECT * from Nation ";//$sql =" INSERT into nation values (' n077 ', ' data ') ";//Execute, The Pdostatement object is returned//$a = $pdo->query ($sql); Execute Query//$a = $pdo->exec ($sql); Execute other statements//var_dump ($a);//$arr = $attr->fetchall (pdo::fetch_both);//var_dump ($arr);//Transaction function/transaction: Ability to control statements while successfully failing simultaneously Can roll back when failed$dsn= "Mysql:dbname=mydb;host=localhost"; Database name, server$pdo=NewPDO ($dsn, "root", "123");//Set Exception mode$pdo->setattribute (pdo::attr_errmode,pdo::errmode_exception); Try{    //Open Transaction    $pdo-BeginTransaction (); $sql 1= "INSERT into nation values (' n080 ', ' delete ')"; $sql 2= "INSERT into nation values (' n070 ', ' several ')"; $sql 3= "INSERT into nation values (' n075 ', ' several ')"; $pdo-exec($sql 1); $pdo-exec($sql 2); $pdo-exec($sql 3);       Three execution success is the same as the relationship, otherwise an error occurs. //Submit    $pdo-commit ();}Catch(Exception $e){    //grab the error that appears in the try and handle the Zv//echo $e->getmessage ();//Get exception information //Rollback    $pdo-rollBack ();}//Final ()//{//final execution, no matter if the above try code is not error, will execute/}?></body>

<?PHP//preprocessing statements to prevent SQL injection$dsn= "Mysql:dbname=mydb;host=localhost";$pdo=NewPDO ($dsn, "root", "123");//$code = "n005"; Do you want to add a placeholder in the//sql statement?//$sql = "SELECT * from Nation where code=?";$sql= "INSERT into nation values (?,?)";//ready to execute, return Pdostatement object$st=$pdo->prepare ($sql);//call the Bind parameter's method to bind the parameter//$st->bindparam (1, $code);//$st->bindparam (2, $name);//$name = "Test 1";//Index array/ /Note the difference$attr=Array("n006", "Test 2");//Execution Method$st->execute ($attr);//$attr = $st->fetchall ();//var_dump ($attr);?>

<?PHP$dsn= "Mysql:dbname=mydb;host=localhost";$pdo=NewPDO ($dsn, "root", "123");//placeholder is a string$sql= "INSERT into nation values (: Code,:name)";$st=$pdo->prepare ($sql);//wait for execution. Prepare preparation//$st->bindparam (": Code", $code, PDO::P aram_str);//$st->bindparam (": Name", $name, PDO::P aram_str); /$code = "n007";//$name = "Test 3";//associative array//with? The difference between placeholders$attr=Array("Code" = "n008", "name" = "Test 4");$st->execute ($attr);?>

PDO Data Access Abstraction Layer