Retrieve part of a MySQL column with PHP - php

Question

For instance, if I have the following table:
+----+---+----------+
| id | a | position |
+----+---+----------+
| 0 | 0 | 0 |
| 1 | 0 | 1 |
| 2 | 1 | 4 |
| 3 | 1 | 9 |
| 4 | 1 | 6 |
| 5 | 1 | 1 |
+----+---+----------+
and I want to get an array that contains the first 100 values from position where a is 1 in ascending order, what would I do?
Im guessing something like this:
$col = mysql_fetch_array( mysql_query('
SELECT `position`
FROM `table`
WHERE `a`="1"
ORDER BY `position` ASC
LIMIT 100
'));
I'd expect to get the following array:
+-------+-------+
| index | value |
+-------+-------+
| 0 | 1 |
| 1 | 4 |
| 2 | 6 |
| 3 | 9 |
+-------+-------+
but it doesn't work.
¿What should I do to make it work?
Thanks

Answer 1

mysql_fetch_array() gets a single row at a time from the result of your query. To access all of the rows you need a loop. Something like...
while ($row = mysql_fetch_array($result, MYSQL_NUM))
{
printf("index: %s value: %s", $row[0], $row[1]);
}
I would take a closer look at: http://php.net/manual/en/function.mysql-fetch-array.php

Answer 2

Okay, couple of things:
Running the mysql_query inside the fetch_array is weird. Mysql_fetch_array works on a query result to put the individual lines of the result(as fetched) into an array. So when you're running it as you've got it, if it runs at all, it's only going to give you the first row, not the first hundred rows.
Second, the quoting looks pretty weird. Depending on the data type in "a", the double quotes might cause. (Haven't used MySQL in a bit, could be wrong.)
If I was going to do it, I'd do it like this:
$result = mysql_query("SELECT index, position FROM table WHERE a = 1 ORDER BY position ASC LIMIT 100");
while($col = mysql_fetch_array($result)){
*do something*
}
*Thanks to JYelton for the Query reformat.

Answer 3

Your query is okay.
The problem is that mysql_fetch_array retrieves only one row. You should loop all the rows and add each value to your $col array.
$result = mysql_query('...');
while($row = mysql_fetch_array($result, MYSQL_NUM))
{
$col[] = $row[0];
}
Now $col contains following:
Array
(
[0] => "1"
[1] => "4"
[2] => "6"
[3] => "9"
)