Show only the last result from mysql row

Question

I have a table

id | field1 | field2 | ... | field[x-1] | field[x]
1  | val1   | val2   | ... | val[x-1]   | val[x]

And I'm doing this search

for($i = 1; $i <= $x; $i++){
   $getvalue = mysql_query("SELECT * FROM table WHERE id='1' AND field".$i." LIKE 'some_value%'")or die(mysql_error());
   while($row = mysql_fetch_array($getvalue)){
      $j=$i+1;
      $val = $row['field'.$j.''];
   }
}

Some values in the table (val[1-x]) will be the same but I need to get only the LAST value. Limit 1 doesn't seem to work.

Update. Unfortunately as David suggested, I can't change the database. It has to be as it is. I have a text file (a settings dump from a sensor) that I insert it line by line into the db and do a check to see if there are any errors. Most check run ok but I have a few lines in that I need to choose only the last one to do the check. I have about 10 lines like this

D?
String
R?
String
...
D?
String
R?
String

I'm interested in the last string after R?. I use explode () and each value checked that they are with in limits.

Answer 1

Using ORDER BY id DESC LIMIT 1:

To get last row (with highest=last=newest id), you should use this:

SELECT * FROM table ORDER BY id DESC LIMIT 1;

Your updated code (with mysqli_ extension) to get last row:

$query= mysqli_query("SELECT * FROM table ORDER BY id DESC LIMIT 1") or die (mysqli_error());
}

$lastRow = mysqli_fetch_row($query);

echo $lastRow['id']; //get the last id

Using MAX():

You also can do it using SQL MAX() function:

SELECT * FROM table WHERE id=(SELECT MAX(id) FROM table)

Answer 2

Managed to get it working as I need it by doing this:

for($i = 1; $i <= 250; $i++){
    $getvalue = mysql_query("SELECT * FROM full_dump WHERE file_name='".$_FILES['datafile']['name']."' AND field_".$i." LIKE ' 100,%'")or die(mysql_error());
    while($row = mysql_fetch_array($getvalue)){
        $i_temp = $i;
    }
}
if($i_temp != NULL){
    $getvalue = mysql_query("SELECT * FROM full_dump WHERE file_name='".$_FILES['datafile']['name']."' AND field_".$i_temp." LIKE ' 100,%'")or die(mysql_error());
    while($row = mysql_fetch_array($getvalue)){
        $r = $row['field_'.$i_temp.''];
    }
}