2 SQL queries at once - mysql

Question

How can I concatenate these two queries, so that I can have 3 columns in my result: postcode, memberCount and placeCount
SELECT LEFT(`delivery_postcode`, 2) as `postcode`, count(`delivery_postcode`) as `count`
FROM `customer_cards`
WHERE `delivery_postcode` IS NOT NULL
AND `delivery_postcode` <> ''
GROUP BY `postcode`
ORDER BY `count` DESC
and
SELECT LEFT(`placePostcode`, 2) as `postcode`, count(`placePostcode`) as `placeCount`
FROM `RestaurantsForGoogleMaps`
WHERE `placePostcode` IS NOT NULL
AND `placePostcode` <> ''
GROUP BY `postcode`
ORDER BY `placeCount` DESC
At the moment my results look like the following, for either query
postcode | count/placeCount
------------------------
SW | 817
W1 | 533
EC | 395

Answer 1

Something like this should work:
SELECT LEFT(`delivery_postcode`, 2) as `postcode`
, count(`delivery_postcode`) as `count`
, pc.placeCount
FROM `customer_cards` cc
LEFT JOIN (
SELECT LEFT(`placePostcode`, 2) as `postcode`,
count(`placePostcode`) as `placeCount`
FROM `RestaurantsForGoogleMaps`
WHERE `placePostcode` IS NOT NULL
AND `placePostcode` <> ''
GROUP BY `postcode`
) pc
on pc.postcode = LEFT(cc.delivery_postcode, 2)
WHERE `delivery_postcode` IS NOT NULL
AND `delivery_postcode` <> ''
GROUP BY `postcode`
ORDER BY `count` DESC

Answer 2

SELECT postcode,count,placecount FROM (SELECT LEFT(`delivery_postcode`, 2) as `postcode`, count(`delivery_postcode`) as `count`, 0 as `placecount`
FROM `customer_cards`
WHERE `delivery_postcode` IS NOT NULL
AND `delivery_postcode` <> ''
GROUP BY `postcode`
UNION
SELECT LEFT(`placePostcode`, 2) as `postcode`, count(`placePostcode`) as `placecount`,0 as `count`
FROM `RestaurantsForGoogleMaps`
WHERE `placePostcode` IS NOT NULL
AND `placePostcode` <> ''
GROUP BY `postcode` ) ORDER BY count desc

Answer 3

At the moment my results look like the following, for either query
;WITH PC1 AS (
SELECT LEFT(`delivery_postcode`, 2) as `postcode`, count(`delivery_postcode`) as `count`
FROM `customer_cards`
WHERE `delivery_postcode` IS NOT NULL
AND `delivery_postcode` <> ''
GROUP BY `postcode`
ORDER BY `count` DESC
),
PC2 AS (
SELECT LEFT(`placePostcode`, 2) as `postcode`, count(`placePostcode`) as `placeCount`
FROM `RestaurantsForGoogleMaps`
WHERE `placePostcode` IS NOT NULL
AND `placePostcode` <> ''
GROUP BY `postcode`
ORDER BY `placeCount` DESC
)
SELECT a.postcode, a.count,b.placeCount
FROM PC1 a
LEFT JOIN PC2 b
ON a.postcode = b.postcode

Answer 4

Create both queries as an inline views and then join on postcode. This assumes both queries return the desired results and that POST CODE is the key on which to join and there are no other attributes needing to complete the join properly. It also assumes the post code would be in both tables.
If not, then we have to replicate the join as right and left and union the results together.
SELECT A.postcode, A.mcount, B.placecount
FROM
(SELECT LEFT(delivery_postcode, 2) as postcode, count(delivery_postcode) as mcount
FROM customer_cards
WHERE delivery_postcode IS NOT NULL
AND delivery_postcode <> ''
GROUP BY LEFT(delivery_postcode, 2)) A
INNER JOIN (
SELECT LEFT(placePostcode, 2) as postcode, count(placePostcode) as placeCount
FROM RestaurantsForGoogleMaps
WHERE placePostcode IS NOT NULL
AND placePostcode <> ''
GROUP BY LEFT(placePostcode, 2)) B
on A.postcode = B.postcode
order by A.postcode