如何从数据库表中获取下一行？

Question

How to get the next row from the Database table? Such that the row might be incremented row that is if structure has a field called "id" then the row can be id++ or very next incremented row, but it may also b any other id containing row (NOT VERY NEXT) , (because the ids could be deleted from the table).

I am using Mysql Database below is my code..

mysql_select_db('pranav_test');
$seletaudit = mysql_query("SELECT * FROM jos_audittrail WHERE live = 0");
while($row2 = mysql_fetch_array($seletaudit))
{
    $audit[] =$row2;
}
$trackid = array();
$tracktable = array();
$i = 0;
foreach($audit as $val)
{
    $trackid[$i] = $val['trackid'];
    $tracktable[$i] = $val['table_name'];   

    if($i!=0)
    {
        $prev_id = $trackid[$i-1];
        $prev_valtab = $tracktable[$i-1];
    }
    if($val['operation'] == 'INSERT')
    {
        if($tracktable[$i]!=$prev_valtab)
        {
            $inserttable = "INSERT INTO '".$tracktable[$i]."' (";
        }


        if($tracktable[$i]==$prev_valtab)
        {
            $insertfield .= "'".$val['field']."', ";
        }
        if($tracktable[$i]==$prev_valtab)
        {
            $insertfield .= "]";
            $insertfield = str_replace(", ]",")",$insertfield);

        }
    }
}

here above I need t know whats going to be my next rows's "table_name" field contain... how can i do that....? Please help for fetching the next row in the for loop to get it checked.

Answer 1

UPDATE :

Ok, now that you posted some code, here a more specific answer:

If you want to have access to the next row in the array, I suggest to use a normal for loop to have access to the index:

for($i = 0; $i<count($audit); $i++) {
     // $audit[$i] is current row
     // $audit[$i+1] is next row
}

But be careful when you reach the end of the array, as $i+1 will be out of bounds.

Or if you just wonder why the $i in your current code is not behaving correctly: You have to increment it at the end of your foreach loop:

$i++;

UPDATE2 :
A more complete example to make it clear (I adapt your approach and check for the previous row)

for($i=0; $i<count($audit);$i++)
{
    $curr = $audit[$i];

    if($i>0) {
        $prev = $audit[$i-1];

        if($curr['operation'] == 'INSERT')
        {
            if($curr['table_name']!=$prev['table_name'])
            {
                $inserttable = "INSERT INTO '".$curr['table_name]."' (";
            }
            else {
                // whereever $insertfield comes from
                $insertfield .= "'".$curr['field']."', ";
                $insertfield .= "]";
                $insertfield = str_replace(", ]",")",$insertfield);

            }
        }
    }
}

---

As you have not specified at all how you connect to the database, here is a generic answer:

Specify your query to order the result set by ID:

$query = "SELECT <columns here> FROM <table here> ORDER BY id";

Then get the result set (we have a fictive database class):

$result = $db->query($query);

Then iterate over the resultset:

while($row = $result->next()) {
    // do something with row
}