ConFoo Montreal 2017 Calling for Papers

SQLite3Stmt::execute

(PHP 5 >= 5.3.0, PHP 7)

SQLite3Stmt::executeExécute une requête préparée

Description

public SQLite3Result SQLite3Stmt::execute ( void )

Exécute une requête préparée et retourne un objet représentant le jeu de résultats.

Liste de paramètres

Cette fonction ne contient aucun paramètre.

Valeurs de retour

Retourne un objet SQLite3Result si la requête préparée a été exécutée avec succès, ou FALSE si une erreur survient.

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gmail@asmqb7
2 months ago
There's currently an issue in the SQLite3 PHP binding (not SQLite3 itself) that causes all queries to be executed twice. It has apparently existed for quite a while.

See here for more info: https://bugs.php.net/bug.php?id=64531

Before discovering the above, I posted this: http://stackoverflow.com/questions/36617708/odd-behavior-with-sqlite3-non-select-prepared-transactions-and-fetcharray (includes copy-paste bug demo)

Workaround: I strongly recommend wrapping any code that might run fetchArray() on non-SELECT query results inside a numColumns() check, like this:

<?php

$op
= $db->prepare(...);

$r = $op->execute(); // query #1

if ($r->numColumns()) { // returns column count, here being used as true/false test
 
while ($row = $r->fetchArray(SQLITE3_ASSOC)) { // query #2
    // your code here
 
}
}

?>

To clarify:

- Query #1 is where the SQLite3 query is executed the first time, query #2 is where the query is executed again. Yes, *everything* is executed twice; this is the bug.

- If your code will only read from and not alter the database (so, a SELECT that won't cause database-altering triggers to run, for example), you're fine. Your query runs twice but it doesn't alter the result.

- If your code will write to the database - for example an INSERT - you MUST not run fetchArray() (and execute the query again) if the number of columns is zero.

- It's not documented in the manual but over here -http://php.net/manual/en/book.sqlite3.php#113144 - user 'bohwaz' mentions that there's also a SQLite3Stmt::readOnly() function since PHP 5.3.11 which will tell you if you just wrote to the DB. This is currently undocumented but might be a more appropriate alternative to numColumns() (I'm not sure what it does, it might be the same).

You might prefer PDO for higher-volume work with SQLite3. This binding is ironically lighter-weight and provides direct access to some SQLite3-specific primitives and behavior... but it runs all queries twice.

[[Note to moderators (this section may be deleted once it has been read; I'm also fine with feedback on the following):

- Please don't consider this comment a bug report - I just want others to be aware of this issue so they don't have to bumble around for hours scratching their heads. :P

- As of the submission date of this comment, there's a unapproved diff for this page stuck in DocBook so I can't add something like "due to bug #64531, you are recommended to wrap fetchArray() inside numColumns()...", which I think would carry more weight than this comment until this bug is fixed.]]
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