Union with Count OR Join with Sum - MySQL - mysql

Question

I want to combine three tables - date, lead and click - in a query.
The tables looks like this:
date:
|date|
lead:
id|time|commission
click:
id|time|commission
The table date is just storing dates and is used when getting dates with no click or lead.
So if we have the following data in the tables:
date:
2009-06-01
2009-06-02
2009-06-03
lead:
1|2009-06-01|400
2|2009-06-01|300
3|2009-06-03|350
click:
1|2009-06-01|1
2|2009-06-03|2
3|2009-06-03|2
4|2009-06-03|0
I would like to get date, number of click, commission generated by clicks (there are clicks that don't give commission), number of leads, commission generated by leads and total commission. So with the tables above I would like to get:
2009-06-01|1|1|2|700|701|
2009-06-02|0|0|0|0|0
2009-06-03|3|4|1|350|354|
I have tried with the following union:
SELECT
campaign_id,
commission_date,
SUM( click_commission ) AS click_commission,
click,
SUM( lead_commission ) AS lead_commission ,
lead,
SUM( total_commission ) as total_commission
FROM(
SELECT
click.campaign_id AS campaign_id,
DATE( click.time ) AS commission_date,
click.commission AS click_commission,
(SELECT count(click.id) from click GROUP BY date(click.time)) as click,
0 as lead_commission,
0 as lead,
click.commission AS total_commission
FROM click
UNION ALL
SELECT
lead.campaign_id AS campaign_id,
DATE( lead.time ) AS commission_date,
0 as click_commission,
0 as click,
lead.commission AS lead_commission,
lead.id as lead,
lead.commission AS total_commission
FROM lead
UNION ALL
SELECT
0 AS campaign_id,
date.date AS commission_date,
0 AS click_commission,
0 as click,
0 AS lead_commission,
0 as lead,
0 AS total_commission
FROM date
) AS foo
WHERE commission_date BETWEEN '2009-06-01' AND '2009-07-25'
GROUP BY commission_date
ORDER BY commission_date LIMIT 0, 10
But this does not work to count both the number of clicks and leads, the code above gives the right amount of clicks bot 0 on all leads. If I move the code around and put the select from the lead table I get the leads right bot 0 on all clicks. I have not been able to find a way to get both of the counts from the query.
So I tried a left-join instead:
SELECT
date.date as date,
count( DISTINCT click.id ) AS clicks,
sum(click.commission) AS click_commission,
count( lead.id ) AS leads,
sum(lead.commission) AS lead_commission
FROM date
LEFT JOIN click ON ( date.date = date( click.time ) )
LEFT JOIN lead ON ( date.date = date( lead.time ) )
GROUP BY date.date
LIMIT 0 , 30
The problem with this query is if there are more than one clicks or leads on a date it will return the expected value * 2. So on 2009-06-01 it will return 1400 instead on the expected 700 for lead commission.
So in the UNION I have problems with the count and in the left join it is the SUM that is not working.
I would really like to stick to the UNION if possible, but I haven't found a way to get both counts from it.
(This is a follow up to this earlier question, but since I didn't ask for the count in that I posted a new question.)

Answer 1

SELECT date,
COALESCE(lcomm, 0), COALESCE(lcnt, 0),
COALESCE(ccomm, 0), COALESCE(ccnt, 0),
COALESCE(ccomm, 0) + COALESCE(lcomm, 0),
COALESCE(ccnt, 0) + COALESCE(lcnt, 0)
LEFT JOIN
(
SELECT date, SUM(commission) AS lcomm, COUNT(*) AS lcnt
FROM leads
GROUP BY
date
) l
ON l.date = d.date
LEFT JOIN
(
SELECT date, SUM(commission) AS ccomm, COUNT(*) AS ccnt
FROM clicks
GROUP BY
date
) с
ON c.date = d.date
FROM date d

Answer 2

The code that I used, built from the suggestion from Quassnoi:
SELECT date,
COALESCE(ccomm, 0) AS click_commission, COALESCE(ccnt, 0) AS click_count,
COALESCE(lcomm, 0) AS lead_commision, COALESCE(lcnt, 0) AS lead_count,
COALESCE(ccomm, 0) + COALESCE(lcomm, 0) as total_commission
FROM date d
LEFT JOIN
(
SELECT DATE(time) AS lead_date, SUM(commission) AS lcomm, COUNT(*) AS lcnt
FROM lead
GROUP BY
lead_date
) l
ON lead_date = date
LEFT JOIN
(
SELECT DATE(time) AS click_date, SUM(commission) AS ccomm, COUNT(*) AS ccnt
FROM click
GROUP BY
click_date
) с
ON click_date = date