Error backup sql database but succeed creating database dump file

Question

I tried this following code to backup mysql database into file and it works perfectly create the .sql file I need.

function backup_tables()
{

$host='localhost';
$user='root';
$pass='';
$name='evote';
$tables = '*';

$link = mysql_connect($host,$user,$pass);
mysql_select_db($name,$link);

//get all of the tables
if($tables == '*')
{
    $tables = array();
    $result = mysql_query('SHOW TABLES');
    while($row = mysql_fetch_row($result))
    {
        $tables[] = $row[0];
    }
}
else
{
    $tables = is_array($tables) ? $tables : explode(',',$tables);
}

//cycle through
foreach($tables as $table)
{
    $result = mysql_query('SELECT * FROM '.$table);
    $num_fields = mysql_num_fields($result);
    
    $return.= 'DROP TABLE '.$table.';';
    $row2 = mysql_fetch_row(mysql_query('SHOW CREATE TABLE '.$table));
    $return.= "\n\n".$row2[1].";\n\n";
    
    for ($i = 0; $i < $num_fields; $i++) 
    {
        while($row = mysql_fetch_row($result))
        {
            $return.= 'INSERT INTO '.$table.' VALUES(';
            for($j=0; $j<$num_fields; $j++) 
            {
                $row[$j] = addslashes($row[$j]);
                $row[$j] = str_replace("\n","\\n",$row[$j]);
                if (isset($row[$j])) { $return.= '"'.$row[$j].'"' ; } else { $return.= '""'; }
                if ($j<($num_fields-1)) { $return.= ','; }
            }
            $return.= ");\n";
        }
    }
    $return.="\n\n\n";
}

//save file
$sql_name='db-backup.sql';
$handle = fopen($sql_name,'w+');
fwrite($handle,$return);
fclose($handle);

return $sql_name;
}

but it shows the error code :

A PHP Error was encountered

Severity: Notice

Message: Undefined variable: return

Filename: models/vote_m.php

can somebody tell me how to fix this?

Joachim Isaksson · Accepted Answer · 2013-06-09 09:06:27Z

1

The first time you reach this line;

$return.= 'DROP TABLE '.$table.';';

...$return has no value to append to. To get rid of the warning, you'll need to initialize $return (to an empty string probably) before starting the loop.

answered Jun 9, 2013 at 9:06

Joachim Isaksson

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2 Comments

user2467703 Over a year ago

when I set $return='' before that line, the database doesn't completely backup. it's just have one table in the .sql file.

Joachim Isaksson Over a year ago

@user2467703 That's why I said before starting the loop (aka before the foreach line) :) If you put it inside the foreach, it will clear it out every iteration instead of just once at the start of the program as intended.

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