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<?php
/**
*
* @package phpBB3
* @copyright (c) 2012 phpBB Group
* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
*
*/
/**
* @ignore
*/
if (!defined('IN_PHPBB'))
{
exit;
}
/**
* Updates rows in given table from a set of values to a new value.
* If this results in rows violating uniqueness constraints, the duplicate
* rows are eliminated.
*
* The only supported tables are bookmarks and topics_watch.
*
* @param dbal $db Database object
* @param string $table Table on which to perform the update
* @param string $column Column whose values to change
* @param array $from_values An array of values that should be changed
* @param int $to_value The new value
* @return null
*/
function phpbb_update_rows_avoiding_duplicates($db, $table, $column, $from_values, $to_value)
{
$sql = "SELECT $column, user_id
FROM $table
WHERE " . $db->sql_in_set($column, $from_values);
$result = $db->sql_query($sql);
$old_user_ids = array();
while ($row = $db->sql_fetchrow($result))
{
$old_user_ids[$row[$column]][] = $row['user_id'];
}
$db->sql_freeresult($result);
$sql = "SELECT $column, user_id
FROM $table
WHERE $column = '" . (int) $to_value . "'";
$result = $db->sql_query($sql);
$new_user_ids = array();
while ($row = $db->sql_fetchrow($result))
{
$new_user_ids[$row[$column]][] = $row['user_id'];
}
$db->sql_freeresult($result);
$queries = array();
$any_found = false;
foreach ($from_values as $from_value)
{
if (!isset($old_user_ids[$from_value]))
{
continue;
}
$any_found = true;
if (empty($new_user_ids))
{
$sql = "UPDATE $table
SET $column = " . (int) $to_value. "
WHERE $column = '" . $db->sql_escape($from_value) . "'";
$queries[] = $sql;
}
else
{
$different_user_ids = array_diff($old_user_ids[$from_value], $new_user_ids[$to_value]);
if (!empty($different_user_ids))
{
$sql = "UPDATE $table
SET $column = " . (int) $to_value. "
WHERE $column = '" . $db->sql_escape($from_value) . "'
AND " . $db->sql_in_set('user_id', $different_user_ids);
$queries[] = $sql;
}
}
}
if ($any_found)
{
$db->sql_transaction('begin');
foreach ($queries as $sql)
{
$db->sql_query($sql);
}
$sql = "DELETE FROM $table
WHERE " . $db->sql_in_set($column, $from_values);
$db->sql_query($sql);
$db->sql_transaction('commit');
}
}
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