Как вернуть несколько значений из хранимой функции в Postrgresql

Я использую PostgreSql, и я новичок в хранимых функциях. Я хочу, чтобы моя хранимая функция возвращала несколько столбцов.

Следующие входные данные отражают столбцы исходной таблицы, в которой хранятся данные от разных пользователей (например, clicks_a, clicks_b, clicks_c, cost_a, cost_b, cost_c и т. д.).

Входные данные: клики, стоимость, бронирования, booking_rev.

Желаемый результат:

month | ttt_group | cpc | monthly_clicks_mln | cvr | margin_per_conversion | monthly_profit | break_even_cpc | ideal_ccp

Я написал следующий код, но я получаю эту ошибку:

ОШИБКА: ссылка на столбец market_segment неоднозначна.

Код:

CREATE OR REPLACE FUNCTION user_performance
     (clicks CHARACTER VARYING, cost CHARACTER VARYING,
      bookings CHARACTER VARYING, booking_rev CHARACTER VARYING)
RETURNS table(month DOUBLE PRECISION, market_segment CHARACTER VARYING, 
              cpc TEXT, monthly_clicks_mln NUMERIC(10,3), cvr TEXT,
              margin_per_conversion TEXT, monthly_profit MONEY, break_even_cpc TEXT, ideal_ccp TEXT)
AS $BODY$

BEGIN

WITH monthly_activity AS (
    SELECT EXTRACT(MONTH FROM date) AS month, market_segment,
        CASE WHEN clicks = 'clicks_a' THEN SUM(clicks_a)
             WHEN clicks = 'clicks_b' THEN SUM(clicks_b)
             WHEN clicks = 'clicks_c' THEN SUM(clicks_c)
        END AS monthly_clicks,
        CASE WHEN cost = 'cost_a' THEN SUM(cost_a)
             WHEN cost = 'cost_a' THEN SUM(cost_b)
             WHEN cost = 'cost_a' THEN SUM(cost_c)
        END AS monthly_cost, 
        CAST(CASE WHEN cost = 'cost_a' AND clicks = 'clicks_a'
             THEN (SUM(cost_a) :: FLOAT /SUM(clicks_a) :: FLOAT)
                  WHEN cost = 'cost_b' AND clicks = 'clicks_b'
             THEN (SUM(cost_b) :: FLOAT /SUM(clicks_b) :: FLOAT)
                  WHEN cost = 'cost_c' AND clicks = 'clicks_c'
             THEN (SUM(cost_c) :: FLOAT /SUM(clicks_c) :: FLOAT)
        END AS DECIMAL(5,4)) AS cpc, 
        CASE WHEN bookings = 'bookings_a' THEN SUM(bookings_a)
             WHEN bookings = 'bookings_b' THEN sum(bookings_b)
             WHEN bookings = 'bookings_c' THEN sum(bookings_c)
        END AS monthly_bookings, 
        CASE WHEN booking_rev = 'booking_rev_a' THEN SUM(booking_rev_a)*15/100
             WHEN booking_rev = 'booking_reb_b' THEN SUM(booking_rev_b)*15/100
             WHEN booking_rev = 'booking_reb_c' THEN SUM(booking_rev_c)*15/100
        END AS monthly_margin
    FROM master_table_2019
    GROUP BY month, market_segment
    ORDER BY month
),

adv_metrics AS (
    SELECT 
        month,market_segment,
        CAST(AVG(cpc) AS DECIMAL(10,3)) AS cpc,
        CAST(AVG(monthly_clicks)/1000000.0 AS DECIMAL(10,3)) AS monthly_clicks_mln,
        CAST(MAX(100.0*monthly_bookings :: FLOAT /monthly_clicks :: FLOAT) AS DECIMAL(3,2)) AS cvr,
        CAST(AVG(monthly_margin :: FLOAT /monthly_bookings :: FLOAT) AS DECIMAL(10,3)) AS margin_per_conversion,
        MAX(monthly_margin - monthly_cost) AS monthly_profit

    FROM monthly_activity
    GROUP BY month, market_segment
    ORDER BY month
)

SELECT
    month, market_segment,
    CONCAT(cpc,' €') AS cpc, 
    monthly_clicks_mln, 
    CONCAT(cvr,'%') AS cvr, 
    CONCAT(margin_per_conversion,' €') AS margin_per_conversion, 
    MONEY(monthly_profit) AS monthly_profit,
    CONCAT(CAST((margin_per_conversion * cvr/100.0) AS DECIMAL(4,3)),' €') AS break_even_cpc,
    CONCAT(CAST((margin_per_conversion * cvr/100.0)*0.85 AS DECIMAL(4,3)),' €') AS ideal_ccp 
FROM adv_metrics
ORDER BY month, market_segment;

END; 
$BODY$ LANGUAGE plpgsql;

SELECT * FROM user_performance('clicks_a', 'cost_a', 'bookings_a', 'booking_rev_a')

Как я могу исправить этот код и заставить его работать?