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이 문서에서는 PHP 중국어 웹사이트 매뉴얼 풀어 주다
[#1] bohwaz [2014-04-21 00:47:00]
Another undocumented feature of the PHP SQLite3 object, available since 2009 is openBlob. Basically it's a function that will return a stream pointer to a blob value in a table. Very very useful when you are dealing with files stored in a SQLite3 database.
Source code says:
proto resource SQLite3::openBlob(string table, string column, int rowid [, string dbname])
Open a blob as a stream which we can read / write to.
But despite that it's not possible to write to the blob, only to read (the write method is empty in the extension source code: it won't return any error but no change will be recorded).
One example of use:
<?php
$db = new SQLite3('files.sqlite');
$db->exec('CREATE TABLE files (id INTEGER PRIMARY KEY, filename TEXT, content BLOB);');
$statement = $db->prepare('INSERT INTO files (filename, content) VALUES (?, ?);');
$statement->bindValue('filename', 'Archive.zip');
$statement->bindValue('content', file_get_contents('Archive.zip'));
$statement->execute();
$fp = $db->openBlob('files', 'content', $id);
while (!feof($fp))
{
echo fgets($fp);
}
fclose($fp);
?>
You can also seek in the stream. This is pretty useful for saving large files from the database too, this way you can use stream_copy_to_stream, it will be faster and more memory-efficient than dumping the file in memory before writing it to the disk.
Please note that openBlob() won't work on VIRTUAL FTS4 compressed tables.
[#2] bohwaz [2013-09-05 04:10:45]
As reported here: https://bugs.php.net/bug.php?id=65216 there are two undocumented and useful methods available:
SQLite3::createCollation(collation name, callback function) appeared in PHP 5.3.11 and allows to define a custom collation method.
SQLite3Stmt::readOnly(void) appeared in PHP 5.3.5 and returns true if a statement doesn't write in the database.
See the documentation pages on the corresponding classes for my comments showing example use of those methods.
[#3] Anonymous [2011-12-06 00:56:46]
As of PHP 5.4 support for Sqlite2 has been removed. I have a large web app that was built with sqlite2 as the database backend and thus it exploded when I updated PHP. If you're in a similar situation I've written a few wrapper functions that will allow your app to work whilst you convert the code to sqlite3.
Firstly convert your DB to an sqlite3 db.
sqlite OLD.DB .dump | sqlite3 NEW.DB
Then add the following functions to your app:
<?php
function sqlite_open($location,$mode)
{
$handle = new SQLite3($location);
return $handle;
}
function sqlite_query($dbhandle,$query)
{
$array['dbhandle'] = $dbhandle;
$array['query'] = $query;
$result = $dbhandle->query($query);
return $result;
}
function sqlite_fetch_array(&$result,$type)
{
#Get Columns
$i = 0;
while ($result->columnName($i))
{
$columns[ ] = $result->columnName($i);
$i++;
}
$resx = $result->fetchArray(SQLITE3_ASSOC);
return $resx;
}
?>
They're not perfect by any stretch but they seem to be working ok as a temporary measure while I convert the site.
Hope that helps someone
[#4] alan at chandlerfamily dot org dot uk [2010-08-09 01:36:53]
PHP 5.3.3 introduced sqlite3::busyTimeout(int milliseconds) which does not currently seem to be documented.
It believe it acts like sqlite::busyTimeout - that is it tells sqlite3 to call an internal busyHandler if SQLITE_BUSY is returned from any call which waits a short period and then retries. It continues to do this until milliseconds milliseconds have elapsed and then returns the SQLITE_BUSY status.
I don't know whether the default 60 second value is in place if this function is not called.