PDO::exec

(PHP 5 >= 5.1.0, PECL pdo >= 0.1.0)

PDO::exec Führt ein SQL Statement aus und gibt die Zahl der betroffenen Zeilen zurück

Beschreibung

public int PDO::exec ( string $statement )

PDO::exec() führt ein SQL Statement aus und gibt die Anzahl der betroffenen Zeilen zurück.

PDO::exec() gibt nicht die Ergebnisse eines SELECT Statements zurück. Um diese zu erhalten kann entweder PDO::query() genutzt werden, oder ein ein PDOStatement, welches über PDO::prepare() erstellt und über PDOStatement::execute() ausgeführt wird.

Parameter-Liste

statement

Das SQL Statement, welches ausgeführt werden soll.

Alle Usereingaben in diesem Query müssen maskiert werden.

Rückgabewerte

PDO::exec() gibt die Anzahl von Zeilen zurück, welche durch diese Abfrage geändert oder gelöscht wurden. Wenn keine Zeilen geändert wurden, gibt PDO::exec() 0 zurück.

Warnung

Diese Funktion kann sowohl das boolsche FALSE zurückliefern, als auch einen nicht-boolschen Wert, welcher zu FALSE ausgewertet wird. Weitere Informationen entnehmen Sie bitte dem Abschnitt über die boolschen Typen. Benutzen Sie deshalb den === Operator, um den Rückgabewert dieser Funktion zu überprüfen.

Das folgende Beispiel verlässt sich fälschlicherweise auf den Rückgabewert von PDO::exec(), weswegen ein Statement, welches 0 Zeilen ändert, einen Aufruf von die() nach sich zieht:

<?php
$db
->exec() or die(print_r($db->errorInfo(), true));
?>

Beispiele

Beispiel #1 Ein DELETE Statement ausführen

Führt das DELETE Statement aus und gibt die Anzahl der gelöschten Zeilen aus.

<?php
$dbh 
= new PDO('odbc:sample''db2inst1''ibmdb2');

/* Entferne alle roten Früchte aus der Tabelle */
$count $dbh->exec("DELETE FROM fruit WHERE colour = 'red'");

/* Und gebe die Anzahl an gelöschten Zeilen zurück */
echo "$count Zeilen wurden gelöscht.\n";
?>

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

10 Zeilen wurden gelöscht.

Siehe auch

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User Contributed Notes 7 notes

up
3
soletan at toxa dot de
8 years ago
It's worth noting here, that - in addition to the hints given in docs up there - using prepare, bind and execute provides more benefits than multiply querying a statement: performance and security!

If you insert some binary data (e.g. image file) into database using INSERT INTO ... then it may boost performance of parsing your statement since it is kept small (a few bytes, only, while the image may be several MiBytes) and there is no need to escape/quote the file's binary data to become a proper string value.

And, finally and for example, if you want to get a more secure PHP application which isn't affectable by SQL injection attacks you _have to_ consider using prepare/execute on every statement containing data (like INSERTs or SELECTs with WHERE-clauses). Separating the statement code from related data using prepare, bind and execute is best method - fast and secure! You don't even need to escape/quote/format-check any data.
up
4
Anonymous
4 years ago
I spent half a day trying to work out why I could not update my sqlite3 database from apache using the PHP PDO driver. I was getting NO error messages at all.

I could connect and select data, but not modify it.

It wasn't until I added the following line:

$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);

after immediately opening the database, that I got a hint of what was happening.

filename: File3
dl_count: 100

( ! ) Warning: PDO::exec() [pdo.exec.html]: SQLSTATE[HY000]: General error: 8 attempt to write a readonly database in /www/htdocs/test/dl-counter/sqlite-readwrite-test.php on line 76
Call Stack
#
Time
Memory
Function
Location
1  0.0086  330120  {main}( )  ../sqlite-readwrite-test.php:0
  2  0.0273  331240  PDO->exec( )  ../sqlite-readwrite-test.php:76

Affected Rows: ''

filename: File3
dl_count: 100

The problem was with the file permissions. As root I could read and write the database from the sqlite3 command line monitor. But Apache was unable to write the database.

Changed the permissions to 755 wwwrun:wwrun and it all works OK!

Thanks again :)
up
3
jon at chem dot umass dot edu
7 years ago
If you do this:

<?php
$res
= $dbh->query("SELECT * FROM sessions                        WHERE session_id = '$p_sessID'");

$l_records = $res->fetch(PDO::FETCH_ASSOC);

if(
$l_records ) {
  
// ...update session-data
  
$l_theQuery = "UPDATE sessions SET session_expires='$newExp', session_data='$p_sessData' WHERE session_id='$p_sessID'";
   echo
$l_theQuery;
  
$l_stmt = $this->db->prepare($l_theQuery);

   if (
$l_stmt ) {
     
$l_rows = $l_stmt->execute();
   }
}
?>

You will get nothing.

But do this:

<?php
$dbh
->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);
?>

Prior to the code above, you will get this:

"PDO::prepare(): SQLSTATE[HY000]: General error: 2014 Cannot execute queries while other unbuffered queries are active. Consider using PDOStatement::fetchAll(). Alternatively, if your code is only ever going to run against mysql, you may enable query buffering by setting the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute."

So, instead of fetch(), use fetchAll(), it will make you less insane.

Incidentally, the INSERT statement that I was issuing, if the record that I needed to update didn't yet exist, after the initial fetch() command worked perfectly.

Changing to fetchAll() fixed it.
up
3
roberto at spadim dot com dot br
7 years ago
this function don't execute multi_query
to get it see SQLITE_EXEC comments there is an pereg function that get all queries and execute all then an return the last one
up
2
david at acz dot org
8 years ago
This function cannot be used with any queries that return results.  This includes SELECT, OPTIMIZE TABLE, etc.
up
-2
hungry dot rahly at gmail dot com
4 years ago
For those that want an exec that handles params like prepare/execute does.  You can simulate this with another function

<?php
class Real_PDO extends PDO {
  public function
execParams($sql, $params) {
   
$stm = $this->prepare($sql);
   
$result = false;
    if(
$stm && $stm->execute($params) ) {
     
$result = $stm->rowCount();
      while(
$stm->fetch(PDO::FETCH_ASSOC) ) {
      }
    }
    return
$result;
  }
}
?>

Remember though, if you are doing a lot of inserts, you'll want to do it the manual way, as the prepare statement will speed up when doing multiple executes(inserts).  I use this so I can place all my SQL statements in one place, and have auto safe quoting against sql-injections.

If you are wondering about the fetch after, remember some databases can return data SELECT-like data from REMOVE/INSERTS.  In the case of PostgreSQL, you can have it return you all records that were actually removed, or have the insert return the records after the insert/post field functions, and io trigger fire, to give you normalized data.

<?php
define
("BLAH_INSERT", "INSERT INTO blah (id,data) VALUES(?,?)");
$pdo = new Real_PDO("connect string");
$data = array("1", "2");
$pdo->execParams(BLAH_INSERT, $data);
?>
up
-4
blah at whatevr dot com
7 years ago
You can't use it not only with SELECT statement, but any statement that might return rows. "OPTIMIZE table" is such example (returns some rows with optimization status).

If you do, PDO will lock-up with the "Cannot execute queries while other unbuffered queries are active." nonsense.
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