PostgreSQL stored function with multiple queries - sql

Question

I'm working on a PostgreSQL function, but having a real struggle with it. It's not my main area so that's probably why, but I wanted to see if this is doable.
I'm trying to create a function to generate records based on year.
In php I'd do something along the lines of:
function recordsByYear($year=''){
$years = array();
if(empty($year)){
$sql = "SELECT year FROM myTable GROUP BY year ORDER BY year;";
$res = $conn->query($sql);
if($res !== false){
$data = $res->fetchAll(PDO::FETCH_COLUMN);
foreach($data as $oneYear){
$years[] = $oneYear;
}
}
}
else{
$years[] = $year;
}
foreach($years as $thisYear){
//do some queries based on $thisYear
}
}
But I'd like to create a function inside of PostgreSQL, and struggling because I'm not familiar enough with how it all works. I'd like to return a table. I can do some basic stuff, but haven't been able to get something like this working where I have one query then loop through those results running an additional query for each year, then combine the results of that second query and spit out the results as a table.

Answer 1

Is hard to guess without more information but you probably need a JOIN
SELECT *
FROM (
SELECT DISTINCT year
FROM myTable
) y
JOIN ( SELECT year, ... <some query>
....
) t
ON y.year = t.year

Answer 2

PostgreSQL function:
CREATE FUNCTION record_years() RETURNS SETOF int AS $$
SELECT DISTINCT year FROM myTable ORDER BY 1
$$ LANGUAGE SQL;
Your PHP code:
$sql = "SELECT record_years()";
or
$sql = "SELECT year FROM record_years() AS year";
or alternatively all values in a single row, as a JSON array:
$sql = "SELECT array_to_json(ARRAY(SELECT record_years())) AS arr";
$res = $conn->query($sql);
if($res !== false){
$row = $res->fetch();
$years[] = json_decode($row['arr']);
}