printing formatted multi-dimensional array from database table

Question

I have a database table with two fields, subject_id, and teacher_id. In the subject_id field are numbers representing subjects like math, science, english. The teacher_id fields represents various teachers. Their presence together on the same row means that teacher 1 teaches subject 2, or on a different row, teacher 1 teaches subject 5, or on a different row teacher 4 teaches subject 2, etc... It is a many-to-many relationship.

After querying from the database, I get an array of this structure:

Array
(
[0] => Array
    (
        [first_name] => bob
        [subject_en_name] => italian
    )

[1] => Array
    (
        [first_name] => bob
        [subject_en_name] => japanese
    )

[2] => Array
    (
        [first_name] => bob
        [subject_en_name] => korean
    )

[3] => Array
    (
        [first_name] => sally
        [subject_en_name] => math
    )

[4] => Array
    (
        [first_name] => sally
        [subject_en_name] => GMAT
    )

)

I need to screen for the first name, and print out a sentence like:

Bob teaches italian, japanese, korean...
Sally teaches math, GMAT...

Using a foreach construction

foreach ($teacher_object as $t_object)
{
    echo $t_object['first_name'] . " teaches " . $t_object['subject_en_name'] . "<br>";

}

I've only been able to manage these printouts:

bob teaches italian
bob teaches japanese
bob teaches korean
sally teaches math
sally teaches GMAT

Is there a php function for sorting array that can help me? Some other solution?

jszobody · Accepted Answer · 2013-12-03 21:51:23Z

4

Rearrange your array first, so that you have a new array with the teacher names as the index, and classes as a sub-array:

$teaches = array();
foreach ($teacher_object as $t_object) {
    $teaches[$t_object['first_name']][] = $t_object['subject_en_name'];
}

The new array will look like this:

Array
(
    [bob] => Array
        (
            [0] => italian
            [1] => japanese
            [2] => korean
        )

    [sally] => Array
        (
            [0] => math
            [1] => GMAT
        )

)

Now you have a much easier array to loop through. Something like this:

foreach($teaches AS $teacher => $classes) {
    echo $teacher . " teaches " . implode(", ",$classes) . "<br/>";
}

Gives you...

bob teaches italian, japanese, korean
sally teaches math, GMAT

edited Dec 3, 2013 at 21:51

answered Dec 3, 2013 at 21:47

jszobody

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