PHP Database Abstraction Layer pdo_php Tutorial

Here's a look at the use of the database abstraction layer PDO:

PDO (PHP Data Objects) is a lightweight PHP extension that provides an abstraction layer of data access. Also, PDO can only be used in versions above PHP5.0.

Here's a look at the predefined constants commonly used by PDO:

PDO::P aram_bool (integer) represents a Boolean data type

PDO::P aram_null (integer) represents a SQL with a data type of NULL

PDO::P aram_int (integer) represented as an integer data type of SQL

PDO::P aram_str (integer) SQL that represents the data type of a char varchar or other string

PDO::P aram_lob (integer) represents an object data type of SQL

Pdo::fetch_lazy (integer) The specified fetch method, which should return each row of the result set as the variable name of an object, corresponding to its field name

pdo::fetch_ori_next (integer) takes the next row of the result set

pdo::fetch_ori_prior (integer) takes the preceding row of the result set

pdo::fetch_ori_first (integer) takes the first row of the result set

pdo::fetch_ori_last (integer) takes the last row of the result set

pdo::attr_persistent (integer) to create a persistent connection instead of creating a new connection

Basic usage of PDO:

Use PDO to connect to the database (only MySQL is used here):
Copy CodeThe code is as follows:
$DBH = new PDO (' Mysql:host=localhost;dbname=test ', $user, $pass);
?>

The following code is the processing of a MySQL connection error:
Copy CodeThe code is as follows:
try {
$DBH = new PDO (' Mysql:host=localhost;dbname=test ', $user, $pass);
foreach ($dbh->query (' SELECT * from FOO ') as $row) {
Print_r ($row);
}
$DBH = null;
} catch (Pdoexception $e) {
Print "error!:". $e->getmessage (). "
";
Die ();
}
?>

Here are two examples of repeated use of INSERT statements:
Copy CodeThe code is as follows:
$stmt = $dbh->prepare ("INSERT into REGISTRY (name, Value) VALUES (: Name,: Value)");
$stmt->bindparam (': Name ', $name);
$stmt->bindparam (': Value ', $value);

Insert one row
$name = ' one ';
$value = 1;
$stmt->execute ();

Insert another row with different values
$name = ' both ';
$value = 2;
$stmt->execute ();
?>

Copy CodeThe code is as follows:
$stmt = $dbh->prepare ("INSERT into REGISTRY (name, value) VALUES (?,?)");
$stmt->bindparam (1, $name);
$stmt->bindparam (2, $value);

Insert one row
$name = ' one ';
$value = 1;
$stmt->execute ();

Insert another row with different values
$name = ' both ';
$value = 2;
$stmt->execute ();
?>

To perform a query operation on a database:
Copy CodeThe code is as follows:
$stmt = $dbh->prepare ("select * from REGISTRY where name =?");
if ($stmt->execute (Array ($_get[' name '))) {
while ($row = $stmt->fetch ()) {
Print_r ($row);
}
}
?>

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