How to add UNION ALL programmatically in a loop? - laravel

Question

I need to construct a query of the following structure:
SELECT
...
FROM table
WHERE
...
GROUP BY
...
UNION ALL
SELECT
...
FROM table
WHERE
...
GROUP BY
...
UNION ALL
SELECT
...
FROM table
WHERE
...
GROUP BY
...
.. and so on..
I get some data in an array, then I iterate it in a foreach loop where I construct each SELECT individually followed by a UNION ALL (except the last).
But I am not able to find a way to add that UNION ALL after every SELECT (Except for the last one):
$query = DB::table('table');
foreach ($data as $item) {
$query->.. // construct the SELECT
$query->unionAll($query); // does not work
}
How can I do it?
Update: Some more accurate code of what I'm using:
$query = DB::table('table');
foreach ($data as $item) {
foreach ($item as $key => $value) {
if (in_array($key, $info) {
$query->addSelect($key);
}
}
$query->selectRaw("COUNT(CASE...)");
$query->selectRaw("COUNT(CASE...)");
foreach ($item as $key => $value) {
if (in_array($key, $info) {
$query->where($key, "=", $value);
}
}
foreach ($item as $key => $value) {
$query->addSelect($key);
}
foreach ($item as $key => $value) {
$query->groupBy($key);
}
}

Answer 1

In this case, unionAll would need to take a new instance of the query builder each time.
You'd either need to set up the initial query outside of the loop or put a check inside the look to set the variable e.g.:
$query = null;
foreach ($data as $item) {
if (!$query) {
$query = DB::table($item['table'])
->where(...) // whatever else you would use to build up the query for the array
;
continue;
}
$query->unionAll(
DB::table($item['table'])
->where(...) // Again, whatever else you would use to build up the query
);
}
$results = $query->get();