Php database abstraction layer PDO_PHP tutorial-php Tutorial

Php database abstraction layer PDO. The following describes how to use the database abstraction layer PDO: PDO (PHPDataObjects) is a lightweight PHP extension that provides a data access abstraction layer. Also, PDO can only introduce the use of the database abstraction layer PDO below:

PDO (PHP Data ObjectsIs a lightweight PHP extension that provides a data access abstraction layer. Also, PDO can only be used in PHP5.0 or later versions.

The following describes the predefined constants commonly used by PDO:

PDO: PARAM_BOOL(Integer) Indicates the Boolean data type.

PDO: PARAM_NULL(Integer) Indicates the SQL statement whose data type is NULL.

PDO: PARAM_INT(Integer) Indicates the SQL statement of the integer data type.

PDO: PARAM_STR(IntegerSQL statement that represents the data type of char varchar or other strings

PDO: PARAM_LOB(Integer) Indicates the SQL statement of the object data type.

PDO: FETCH_LAZY(Integer) The specified method of obtaining. each row of the result set should be returned as the variable name of an object, corresponding to its field name.

PDO: FETCH_ORI_NEXT(Integer)Returns the next row of the result set.

PDO: FETCH_ORI_PRIOR(Integer)Get the row before the result set

PDO: FETCH_ORI_FIRST(Integer)The first row of the result set.

PDO: FETCH_ORI_LAST(Integer)Returns the last row of the result set.

PDO: ATTR_PERSISTENT(IntegerInstead of creating a new connection.

Basic usage of PDO:

Use PDO to connect to the database (MySQL only ):

The code is as follows:

$ Dbh = new PDO ('MySQL: host = localhost; dbname = test', $ user, $ pass );
?>

The following code is used to handle MySQL connection errors:

The 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 ();
}
?>

The following are two examples of repeated insert statements:

The 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 = 'two ';
$ Value = 2;
$ Stmt-> execute ();
?>

The 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 = 'two ';
$ Value = 2;
$ Stmt-> execute ();
?>

Query a database:

The 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 );
}
}
?>

PDO (PHP Data Objects) is a lightweight PHP extension that provides a Data access abstraction layer. Also, PDO can only be used in...