PHP / SQLite - Copying a table from disk to memory

php, sqlite

Solution

Not a pdo-specific solution that may or may not be sufficient in your case:

- create a :memory: database

- Attach the existing database file

- CREATE TABLE ... AS SELECT * FROM ...

- Detach the database file

edit: an example First an example database stored in mydb.sq3

<?php
$pdo = new PDO('sqlite:mydb.sq3');
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

$pdo->exec('CREATE TABLE foo(x INTEGER PRIMARY KEY ASC, y, z)');

$stmt = $pdo->prepare("INSERT INTO foo (x,y,z) VALUES (:x,:y,:z)");
$stmt->bindParam(':x', $x);
$stmt->bindParam(':y', $y);
$stmt->bindParam(':z', $z);

for($x=0; $x<100; $x++) {
    $y = $x*2;
    $z = $x*2+1;
    $stmt->execute();
}

Now we have a :memory: database and want to transfer the table foo

<?php
$pdo = new PDO('sqlite::memory:');
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

$pdo->exec('ATTACH "mydb.sq3" as filedb');
$pdo->exec('CREATE TABLE bar AS SELECT * FROM filedb.foo');
$pdo->exec('DETACH filedb');

Done. But let's take a look at the sqlite_master table

foreach($pdo->query('SELECT sql FROM sqlite_master') as $row) {
    echo $row['sql'];
}

this prints

CREATE TABLE bar(x INT,y,z)

The INTEGER PRIMARY KEY ASC declaration is lost. Might be sufficient though....

Problem

I have a sqlite3 database on my harddrive (file.db) with 5 tables. I'd like to copy 3 of these tables to an in-memory database (:memory:). Is there a simple way to do so using PHP5's PDO format?

Original source