Full Outer Join, Coalesce, and Group By (Oh My!) - sql

Question

I'm going to ask this in two parts, because my logic may be way off, and if so, the syntax doesn't really matter.
I have 10 queries. Each query returns month, supplier, and count(some metric). The queries use various tables, joins, etc. Not all month/supplier combinations exist in the output for each query. I would like to combine these into a single data set that can be exported and pivoted on in Excel.
I'd like the output to look like this:
Month | Supplier | Metric1 |Metric2 |..| Metric 10
2018-01 | Supp1 | _value_ | _value_ |...| _value_ |
2018-01 | Supp2 | NULL | _value_ |...| NULL
What is the best / easiest / most efficient way to accomplish this?
I've tried various methods to accomplish the above, but I can't seem to get the syntax quite right. I wanted to make a very simple test case and build upon it, but I only have select privileges on the db, so I am unable to test it out. I was able to create a query that at least doesn't result in any squiggly red error lines, but applying the same logic to the bigger problem doesn't work.
This is what I've got:
create table test1(name varchar(20),credit int);
insert into test1 (name, credit) values ('Ed',1),('Ann',1),('Jim',1),('Ed',1),('Ann',1);
create table test2 (name varchar(10), debit int);
insert into test2 (name, debit) values ('Ann',1),('Sue',1),('Sue',1),('Sue',1);
select
coalesce(a.name, b.name) as name,
cred,
deb
from
(select name, count(credit) as cred
from test1
group by name) a
full outer join
(select name, count(debit) as deb
from test2
group by name) b on
a.name =b.name;
Am I headed down the right path?
UPDATE: Based on Gordon's input, I tried this on the first two queries:
select Month, Supp,
sum(case when which = 1 then metric end) as Exceptions,
sum(case when which = 2 then metric end) as BackOrders
from (
(
select Month, Supp, metric, 1 as which
from (
select (convert(char(4),E.PostDateTime,120)+'-'+convert(char(2),E.PostDateTime,101)) as Month, E.TradingPartner as Supp, count(distinct(E.excNum)) as metric
from db..TrexcMangr E
where (E.DSHERep in ('AVR','BTB') OR E.ReleasedBy in ('AVR','BTB')) AND year(E.PostDateTime) >= '2018'
) a
)
union all
(
select Month, Supp, metric, 2 as which
from (
select (convert(char(4),T.UpdatedDateTime,120)+'-'+convert(char(2),T.UpdatedDateTime,101)) as Month, P.Supplier as Supp, count(*) as metric
from db1..trordertext T
inner join mdid_Tran..trOrderPO P on P.PONum = T.RefNum
where T.TextType = 'BO' AND (T.CreatedBy in ('AVR','BTB') OR T.UpdatedBy in ('AVR','BTB')) AND year(UpdatedDateTime) >=2018
) b
)
) q
group by Month, Supp
... but I'm getting a group by error.

Answer 1

One method uses union all and group by:
select month, supplier,
sum(case when which = 1 then metric end) as metric_01,
sum(case when which = 2 then metric end) as metric_02,
. . .
from ((select Month, Supplier, Metric, 1 as which
from (<query1>) q
. . .
) union all
(select Month, Supplier, Metric, 2 as which
from (<query2>) q
. . .
) union all
. . .
) q
group by month, supplier;

Answer 2

SELECT
CalendarMonthStart,
Supp,
SUM(CASE WHEN metric_id = 1 THEN metric END) as Exceptions,
SUM(CASE WHEN metric_id = 2 THEN metric END) as BackOrders
FROM
(
SELECT
DATEADD(month, DATEDIFF(month, 0, E.PostDateTime), 0) AS CalendarMonthStart,
E.TradingPartner AS Supp,
COUNT(DISTINCT(E.excNum)) AS metric,
1 AS metric_id
FROM
db..TrexcMangr E
WHERE
( E.DSHERep in ('AVR','BTB')
OR E.ReleasedBy in ('AVR','BTB')
)
AND E.PostDateTime >= '2018-01-01'
GROUP BY
1, 2
UNION ALL
SELECT
DATEADD(month, DATEDIFF(month, 0, T.UpdatedDateTime), 0) AS CalendarMonthStart,
T.UpdatedDateTime,
P.Supplier AS Supp,
COUNT(*) AS metric,
2 AS metric_id
FROM
db1..trordertext T
INNER JOIN
mdid_Tran..trOrderPO P
ON P.PONum = T.RefNum
WHERE
( T.CreatedBy in ('AVR','BTB')
OR T.UpdatedBy in ('AVR','BTB')
)
AND T.TextType = 'BO'
AND T.UpdatedDateTime >= '2018-01-01'
GROUP BY
1, 2
)
combined
GROUP BY
CalendarMonthStart,
Supp