Question

I have a MySQL query that I am saving to a variable to output on the page. I have the data in an unordered list, but I am trying to split the data into three columns using 3 unordered lists floated left. Here is my current code:

        $sqlCommand = 
           "SELECT  list_specialty.id, list_specialty.specialty  FROM list_specialty
            ORDER BY list_specialty.specialty ASC";
        $query = mysqli_query($myConnection,$sqlCommand) or die (mysqli_error($myConnection));

        $specialtyDisplay = '';

        $num = mysqli_num_rows($query);
        $split = intval($num/3); //number of items in every column

        $i = 0;

        while ($row = mysqli_fetch_array($query)) {
            $specialtyid = $row["id"];
            $specialtyname = $row["specialty"];

            $specialtyDisplay .= 
                '<li><a href="doctor.php?specialty=' . $specialtyid . '">' . $specialtyname . '</a></li>';
            $i++;
            if ($i == $split) {
                $specialtyDisplay .= '</ul> <ul>';
                $i = 0;
            }

        }

This code works GREAT as long as my data is exactly divisible by 3 (equal columns).
However, when my total number of rows is not divisible by 3, the above code won’t work.

I need a solution that will balance the columns, so I can have either 3 equal columns, one extra element in the first column, or one extra element in the first and second column.

What do I need to change in my code to account for that?

Answer 1

This will work:

1. set $split to the length of the longest column
2. rows have 0, 1 or 2 columns that are longer by one element. -> $longcols = $num % 3
3. substract 1 from $split when column number $longcols is printed (unless all columns have equal length)

Implemented in the code:

$num = mysqli_num_rows($query);
$split = ceil($num/3); // 1.

$i = 0;
$col = 1; //for counting columns
$longcols = $num % 3; // 2.

while ($row = mysqli_fetch_array($query)) {
    $specialtyid = $row["id"];
    $specialtyname = $row["specialty"];

    $specialtyDisplay .= 
        '<li><a href="doctor.php?specialty=' . $specialtyid . '">' . $specialtyname . '</a></li>';
    $i++;
    if ($i == $split) {
        $specialtyDisplay .= '</ul> <ul>';

        if( $longcols != 0 && $longcols == $col ) { $split--; } // 3.
        $i = 0;
        $col++; //increase columns count
    }

}

The lines with comments are those that I have changed/inserted.