PostgreSQL – Function Without Parameters and Calling a Function Inside

postgresql

I'm new with PostgreSQL and feeling quite overwhelmed..

What I'm trying to achieve is something like this:

Wanted outcome

year descrip percent
2019 Word word word 0.10
2018 Word word sad 0.80
2017 Word empty word 0.15
etc Word word word 0.41

Where percent is function_A divided by function_B** (function_A / function_B).

I already have the functions

  • function_A has two parameters : year (extracted from status_date) and code. Returns the number of orders defined by the previous
    parameters.
  • function_B has one parameter: year (extracted from status_date).
    Returns the total number of orders by year.

Function

This is what, wrongly, I did so far – including code from nbk's original answer:

The function shouldn't have any parameters.

CREATE OR REPLACE FUNCTION summary_orders()
RETURNS TABLE (retyear numeric, order_desc text, percentage bigint) AS $$
DECLARE
    retyear numeric DEFAULT 0;
    descrip text DEFAULT 0;
    percent bigint DEFAULT 0;
BEGIN
    RETURN
        QUERY SELECT CAST(EXTRACT(year FROM created_dt) as numeric),
                order_desc as text,
                ROUND(function_A(inyear,incode))::decimal / function_B(inyear) as percent
        FROM orders o
        WHERE EXTRACT(YEAR FROM o.creation) = inyear
        AND o.order_code = incode
        AND o.descrip 
        GROUP BY EXTRACT(year FROM o.creation), o.code
        ORDER BY retyear ASC;
END;
$$
LANGUAGE plpgsql;

To call the function I expect to use:

SELECT * from summary_code()

My data looks something like this:

'orders' Table

CREATE TABLE orders (
    id INT NOT NULL, 
    code INT NOT NULL, 
    service_id INT NOT NULL, 
    descript CHARACTER VARYING(50), 
    creation TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    status_date TIMESTAMP,
    created_user INT
    );

Records

INSERT INTO orders 
(id, code, service_id, descript, creation, status_date, created_user) 
VALUES 
(100,2394,558151,'Requested not today','2019-06-16 11:12','2019-06-18 14:08',1),
(100,2394,558151,'Fulfilled blue squit','2018-06-16 11:12','2018-06-18 14:08',1),
(100,2394,558151,'Requested blue kit','2019-06-16 11:12','2019-06-18 14:08',1),
(100,2395,558152,'Requested pony','2019-06-16 11:12','2019-06-18 14:08',1),
(100,2396,558153,'Requested sauron','2019-06-16 11:12','2019-06-18 14:08',1),
(100,2394,558151,'Requested I'm tired','2019-06-16 11:12','2019-06-18 14:08',1);

I'm sorry if this comes as a little cheeky, but I don't know where to start.

Best Answer

CREATE TABLE orders (
    id INT NOT NULL, 
    code INT NOT NULL, 
    service_id INT NOT NULL, 
    descript CHARACTER VARYING(50), 
    creation TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    status_date TIMESTAMP,
    created_user INT
    );

INSERT INTO orders 
(id, code, service_id, descript, creation, status_date, created_user) 
VALUES 
(100,2394,558151,'Requested not today','2019-06-16 11:12','2019-06-18 14:08',1),
(100,2394,558151,'Fulfilled blue squit','2018-06-16 11:12','2018-06-18 14:08',1),
(100,2394,558151,'Requested blue kit','2019-06-16 11:12','2019-06-18 14:08',1),
(100,2395,558152,'Requested pony','2019-06-16 11:12','2019-06-18 14:08',1),
(100,2396,558153,'Requested sauron','2019-06-16 11:12','2019-06-18 14:08',1),
(100,2394,558151,'Requested I''m tired','2019-06-16 11:12','2019-06-18 14:08',1);

CREATE FUNCTION function_A(in numeric, in int,out noorder int)
    AS $$ SELECT COUNT(*) FROM orders WHERE EXTRACT(YEAR FROM  "status_date") = $1 AND "code" = $2 $$
    LANGUAGE SQL;

CREATE FUNCTION function_B(in numeric,out noorderyear int)
    AS $$ SELECT COUNT(*) FROM orders WHERE EXTRACT(YEAR FROM  "status_date") = $1  $$
    LANGUAGE SQL;

CREATE OR REPLACE FUNCTION summary_orders()
RETURNS TABLE (retyear numeric, order_desc TEXT, percentage numeric) AS $$
DECLARE
    retyear numeric DEFAULT 0;
    descrip TeXT DEFAULT 0;
    percent numeric DEFAULT 0;
BEGIN
    RETURN
        QUERY SELECT CAST(EXTRACT(year FROM status_date) as numeric) teayear,
                MIN(descript) as descrip,
                ROUND(Max(function_A(CAST(EXTRACT(year FROM status_date) as numeric),code))::decimal / function_B(CAST(EXTRACT(year FROM status_date) as numeric)),2) as percent
        FROM orders o
        GROUP BY teayear
        ORDER BY teayear ASC;
END;
$$
LANGUAGE plpgsql;

SELECT * FROM summary_orders()

retyear | order_desc           | percentage
------: | :------------------- | ---------:
   2018 | Fulfilled blue squit |       1.00
   2019 | Requested blue kit   |       0.60

db<>fiddle here

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