How can you loop through a mysql_fetch_array() with a for loop?

Question

I am doing a MySQL SELECT on my database with PHP and I want to loop through the results. I am using mysql_fetch_array() to do this. I was originally using a while loop to loop through the results the problem I encountered is that in the loop I need to get what row the loop is currently in. I thought a for loop would do this because then I would have $i to get the value of the problem is that I do not think it will work. Below is my code. Is it possible to do what I am asking and am I doing it the right way?

$q = "SELECT test_id, title, subject, type, creation_date FROM tests WHERE user_id='$user_id' LIMIT 10"; //select first ten of users tests
$r = mysqli_query ($dbc, $q) or trigger_error("Query: $q\n<br />MySQL Error: " . mysqli_error($dbc));

if (mysqli_affected_rows($dbc) > 0) {//if the query ran correctly and the test details were gathered from the database

$row = mysqli_fetch_array($r, MYSQLI_ASSOC)

for($i=1; i<10; i++) {

$test_id = $row['test_id'];
$test_type = $row['type'];
$creation_date = $row['creation_date'];
$creator = $user_id;
$title = $row['title'];
$subject = $row['subject'];

$q = "SELECT tag_id FROM test_tags WHERE test_id='$test_id[$i]"; //select tags corresponding to this test
$r = mysqli_query ($dbc, $q) or trigger_error("Query: $q\n<br />MySQL Error: " . mysqli_error($dbc));

}

Jon Gauthier · Accepted Answer · 2011-04-16 22:22:18Z

5

Use the while loop like you did before and just keep a variable $i which is incremented once per iteration.

$q = "SELECT test_id, title, subject, type, creation_date FROM tests WHERE user_id='$user_id' LIMIT 10"; //select first ten of users tests
$r = mysqli_query ($dbc, $q) or trigger_error("Query: $q\n<br />MySQL Error: " . mysqli_error($dbc));

if (mysqli_affected_rows($dbc) > 0) {//if the query ran correctly and the test details were gathered from the database

    $row = mysqli_fetch_array($r, MYSQLI_ASSOC)
    $i = 0;

    while ( $row = mysqli_fetch_array($r, MYSQLI_ASSOC) ) {
        $test_id = $row['test_id'];
        $test_type = $row['type'];
        $creation_date = $row['creation_date'];
        $creator = $user_id;
        $title = $row['title'];
        $subject = $row['subject'];

        $q = "SELECT tag_id FROM test_tags WHERE test_id='$test_id[$i]"; //select tags corresponding to this test
        $r2 = mysqli_query ($dbc, $q) or trigger_error("Query: $q\n<br />MySQL Error: " . mysqli_error($dbc));

        $i += 1;
    }
}

answered Apr 16, 2011 at 22:22

Jon Gauthier

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1 Comment

mickmackusa Over a year ago

Why is there a fetching line of code before the loop that does the same action?

starsinmypockets · Accepted Answer · 2011-04-16 23:00:46Z

I would use the foreach() construction to loop through the result object. Something like this:

//select first ten of users tests
$q = "SELECT test_id, title, subject, type, creation_date FROM tests WHERE user_id='$user_id' LIMIT 10"; 
$r = mysqli_query($dbc, $q);
$i = 0;
//loop through result object:
foreach ($r as $row) {
  $row[$i]['test_id'] = $test_id;
  //...

  $q = "SELECT tag_id FROM test_tags WHERE test_id='$test_id[$i]"; //select tags corresponding to this test
  $r = mysqli_query ($dbc, $q) or trigger_error("Query: $q\n<br />MySQL Error: " . mysqli_error($dbc));

  //loop through the new result:

  foreach ($r as $tag) {
    $tags[] = $tag;
  }

  $i++; //increment counter.

  //Not sure where you're going from here, but...

  $row[$i]['tags'] = $tag; //add tags array to $row
  return $row[$i];
}

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