I have a situation where I have a table of incidents and a table of actions. The relationship is one incident has many actions.

I require the need to display via a web page, a list of incidents IDs and their relevant actions thus:

Indicent 1
- Action 1
- Action 2
- Action 3
Indicent 2
- Action 4
Incident 3
- Action 5
- Action 6

Currrently, I just retrieve a set of actions and can sort them by incident ID. However I would like each action grouped by incident, and the incident ID to be displayed just the once before each group of actions.

I currently have in one subroutine: 
my $sql =
"
SELECT
incident.id AS i_id, incident.severity, incident.summary,
action.id AS a_id, action.incident_id, action.description, action.note
+s
FROM
incident,
action
WHERE
incident.id = action.incident_id
AND action.due_date > $date (a specified date)
AND action.due_date < current_date()
ORDER BY sort_date ASC
"

$sth->prepare($sql);
$sth->execute();

while (my $href =$sth->fetchrow_hashref()) {
my $details={};
$details->{'Incident ID'} = $$href{'i_id'};
$details->{'Action ID'} = $$href{'a_id'};
$details->{'Severity'} = $$href{'severity'};
$details->{'Summary'} = $$href{'summary'};
and so on...

push(my @results, $details);
}
return @results

[download]
And in another subroutine:
my @results = "first subroutine"

foreach my $result (@results) {
my $output = $result->{'Incident ID'}.", ";
$output .= $result->{'Action ID'}.", ";
$output .= $result->{'Severity'}.", ";
$output .= $result->{'Summary'}.", ";
and so on...
$counter++
}
return $output;

[download]
This will return something along the following lines:

1, 1, Severe, A severe incident
1, 2, Severe, A severe incident
1, 3, Severe, A severe incident
2, 4, Minor, A minor incident
2, 5, Minor, A minor incident

I would like something like:

1, Severe, A severe incident
-> 1 (action id, with further columns from the action table)
-> 2
-> 3
2, Minor, A minor incident
-> 4
-> 5

What's the easiest way to do this?

In reply to Perl/SQL query - grouping 'one to many' records by pcdj_d

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