PDO Functions Library in PHP_PHP Tutorial

PDO is a "database access abstraction layer" that unifies the access interfaces of various databases. Compared with the function libraries of mysql and mysqli, PDO makes cross-database use more friendly; compared with ADODB and MDB2, PDO is more efficient. At present, there is a long way to go to implement the "database abstraction layer". Using a "database access abstraction layer" such as PDO is a good choice.

PDO->beginTransaction() — marks the starting point of rollback
PDO->commit() — Mark the rollback end point and execute SQL
PDO->__construct() — Create an instance of PDO linked database
PDO->errorCode() — Get error code
PDO->errorInfo() — Get error information
PDO->exec() — Process a SQL statement and return the number of entries affected
PDO->getAttribute() — Get the attributes of a "database connection object"
PDO->getAvailableDrivers() — Get valid PDO driver names
PDO->lastInsertId() — Get the primary key value of the last piece of data written
PDO->prepare() — generate a "query object"
PDO->query() — Process a SQL statement and return a "PDOStatement"
PDO->quote() — Add quotes to a string in SQL
PDO->rollBack() — Perform a rollback
PDO->setAttribute() — Set attributes for a "database connection object"
PDOStatement->bindColumn() — Bind a column to a PHP variable
PDOStatement->bindParam() — Binds a parameter to the specified variable name
PDOStatement->bindValue() — Binds a value to a parameter
PDOStatement->closeCursor() — Closes the cursor, enabling the statement to be executed again.
PDOStatement->columnCount() — Returns the number of columns in the result set
PDOStatement->errorCode() — Fetch the SQLSTATE associated with the last operation on the statement handle
PDOStatement->errorInfo() — Fetch extended error information associated with the last operation on the statement handle
PDOStatement->execute() — Executes a prepared statement
PDOStatement->fetch() — Fetches the next row from a result set
PDOStatement->fetchAll() — Returns an array containing all of the result set rows
PDOStatement->fetchColumn() — Returns a single column from the next row of a result set
PDOStatement->fetchObject() — Fetches the next row and returns it as an object.
PDOStatement->getAttribute() — Retrieve a statement attribute
PDOStatement->getColumnMeta() — Returns metadata for a column in a result set
PDOStatement->nextRowset() — Advances to the next rowset in a multi-rowset statement handle
PDOStatement->rowCount() — Returns the number of rows affected by the last SQL statement
PDOStatement->setAttribute() — Set a statement attribute
PDOStatement->setFetchMode() — Set the default fetch mode for this statement

As can be seen from the function list, operations are based on different objects. "PDO" represents a database connection object (produced by new PDO), and "PDOStatement" represents a query object (produced by PDO->query() ) or a result set object (produced by PDO->prepare()).
An example of a "Database Connection Object", returning "PDO":
$dbh = new PDO(mysql:host=localhost;dbname=test, root, );
?>

An example of "query object", returning "PDOStatement":
$sql = "INSERT INTO `test`.`table` (`name` ,`age`)VALUES (?, ?);";
$stmt = $dbh->prepare($sql);
?>

An example of a "result set object", returning "PDOStatement":
$sql = "SELECT * FROM `table` WHERE `name` = samon";
$stmt = $dbh->query($sql);
?>

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