I'm trying to get the average number of interactions on my metrics, but this query gets the average number of inteactions for those who DID interact (those in metricsActions are only there if they HAVE interacted, their metricsID still exists in metrics table).
So, I'm wondering how I can get the average of all those users. I can do two queries, but then how would I average with the two results? Is it possible to merge?
SELECT AVG(`instances`) FROM (SELECT m.`metricID`, COUNT(mc.`metricAction`) as `instances` FROM `metricActions` mc LEFT JOIN `metrics` m ON m.`metricID` = mc.`metricID` WHERE m.`clientID` = '10412' AND `type` = '2' AND GROUP BY mc.`metricID` ORDER BY `instances` DESC ) as `temp`
You should use the LEFT JOIN the other way around:
SELECT AVG(`instances`)
FROM (
SELECT m.`metricID`, COUNT(mc.`metricAction`) as `instances`
FROM `metrics` m
LEFT JOIN
`metricActions` mc
ON mc.`metricID` = m.`metricID`
AND mc.`type` = '2'
WHERE m.`clientID` = '10412'
GROUP BY
m.`metricID`
) as `temp`
Related
I'm trying to substitute my join SQL code to a different code without any of JOIN statements for faster data retrieval. However, i'm getting the error below.
#1242 - Subquery returns more than 1 row
What i would like to do, get all rows from one table 'tbl_my_itemlist' and JOIN to other more tables, tbl_register and tbl_register without using JOIN statements.
The Code using JOIN statement (works fine).
SELECT
tbl_screenshots.screenshot_image_url,
mit.my_itemlist_id,
mit.item_name,
mit.item_initial_cost,
mit.item_offer_cost,
mit.offer_date_from,
mit.offer_date_to
FROM
(
SELECT
my_itemlist_id
FROM
tbl_my_itemlist
WHERE
offer_date_from >='2020-10-20' AND offer_date_to <= '2020-10-30' AND
item_deleted_status = 'active'
) mlist
JOIN tbl_my_itemlist mit ON
mit.my_itemlist_id = mlist.my_itemlist_id
RIGHT JOIN tbl_screenshots ON mit.my_itemlist_id =
tbl_screenshots.my_itemlist_id
RIGHT JOIN tbl_register ON tbl_register.register_id = mit.register_id
GROUP BY
mit.my_itemlist_id
ORDER BY mit.offer_date_to ASC LIMIT 2
The code i'm substituting the JOIN statement code with.
SELECT
mit.my_itemlist_id,
mit.item_name,
mit.item_initial_cost,
mit.item_offer_cost,
mit.offer_date_from,
mit.offer_date_to,
(
SELECT
reg.business_name
FROM
tbl_register reg
WHERE
reg.register_id = mit.register_id
) reg_sql,
(
SELECT
sshots.screenshot_image_url
FROM
tbl_screenshots sshots
WHERE
sshots.my_itemlist_id = mit.my_itemlist_id
) sshots_sq
FROM
tbl_my_itemlist mit
WHERE
mit.offer_date_from >= '2020-10-20' AND mit.offer_date_to <= '2020-10-30' AND mit.item_deleted_status = 'active'
GROUP BY
mit.my_itemlist_id
ORDER BY
mit.offer_date_to ASC
LIMIT 2
I'm trying to build an SQL query that can retrieve data from million records within very short period of time as compared to using the JOIN statement.
I have three tables named issue_details, nature_payments, and rci_records. Now I have this query which joins this three tables.
SELECT issue_details.issue_date AS Date,
issue_details.check_no AS Check_No,
payees.payee_name AS Name_payee,
nature_payments.nature_payment AS Nature_of_Payment,
issue_details.issue_amount AS Checks_issued,
issue_details.nca_balance AS Nca_balance
FROM
issue_details
INNER JOIN
nature_payments ON
issue_details.nature_id = nature_payments.nature_id
INNER JOIN
payees ON
issue_details.payee_id = payees.payee_id
ORDER BY Date Asc, Check_no ASC
On my column in Nca_balance, this is a computed differences of every issuances of check. But you may not know what really the process of how I got the difference but to make it simple, let's say that I have another query
that dynamically get also the difference of this nca_balance column. Here is the query:
SELECT r.*,
(#tot := #tot - issue_amount) as bank_balance
FROM (SELECT #tot := SUM(nca_amount) as nca_total FROM nca
WHERE account_type = 'DBP-TRUST' AND
year(issue_date) = year('2015-01-11') AND
month(issue_date) = month('2015-01-11')
)
vars CROSS JOIN issue_details r
WHERE r.account_type = 'DBP-TRUST' AND
r.issue_date = '2015-01-11'
ORDER BY r.issue_date, r.check_no
I know it you may not get my point but I just want to replace the first query of the line
issue_details.nca_balance AS Nca_balance
with my own computation on my second query.
Please help me combine those two query into a single query. Thanks
I'm working with the join plus union plus group by query, and I developed a query something like mentioned below:
SELECT *
FROM (
(SELECT countries_listing.id,
countries_listing.country,
1 AS is_country
FROM countries_listing
LEFT JOIN product_prices ON (product_prices.country_id = countries_listing.id)
WHERE countries_listing.status = 'Yes'
AND product_prices.product_id = '3521')
UNION
(SELECT countries_listing.id,
countries_listing.country,
0 AS is_country
FROM countries_listing
WHERE countries_listing.id NOT IN
(SELECT country_id
FROM product_prices
WHERE product_id='3521')
AND countries_listing.status='Yes')) AS partss
GROUP BY id
ORDER BY country
And I just realised that this query is taking a lot of time to load results, almost 8 seconds.
I was wondering if there is the possibility to optimize this query to the fastest one?
If I understand the logic correctly, you just want to add a flag for the country as to whether or not there is a price for a given product. I think you can use an exists clause to get what you want:
SELECT cl.id, cl.country,
(exists (SELECT 1
FROM product_prices pp
WHERE pp.country_id = cl.id AND
pp.product_id = '3521'
)
) as is_country
FROM countries_listing cl
WHERE cl.status = 'Yes'
ORDER BY country;
For performance, you want two indexes: countries_listing(status, country) and
product_prices(country_id, product_id)`.
Depending on how often it is executed, prepared statements could help. See PDO for more information.
I have two mysql tables with content one is called petitions
{"success":1,"petitions":[{"id":"6","name":"should he go","timestamp":"2013-10-26 03:02:44"},{"id":"3","name":"Olara Otunu should get married","timestamp":"2013-10-24 14:33:53"},{"id":"4","name":"Teachers deserve 30 not 20 salary rise","timestamp":"2013-10-24 14:33:53"},{"id":"5","name":"Prostitution should be banned","timestamp":"2013-10-24 14:33:53"},{"id":"1","name":"Has Jennifer Musisi done great work for Kampala","timestamp":"2013-10-24 14:32:58"},{"id":"2","name":"Do lecturers deserve 100% salary increase","timestamp":"2013-10-24 14:32:58"}]}
and the other table is called petition_response
{"success":1,"petition_response":[{"id":"2","petitionID":"2","yes":"0","no":"1","memberID":"14","timestamp":"2013-11-02 08:36:20"},{"id":"1","petitionID":"1","yes":"1","no":"0","memberID":"14","timestamp":"2013-11-01 21:26:02"}]}
I need to select * petitions which have no response in the petition_response. But if they have any response in the petition_response table then the memberID should not be equal to 14
I have tried this code below but its not working
$result = mysql_query("select * from petition_response where memberID='14' order by timestamp DESC", $db->connect());
while($row = mysql_fetch_assoc($result)){
$id = $row['id'];
$result2 = mysql_query("select * from petitions where id != '$id' order by timestamp DESC", $db->connect());
}
return $result2;
You're looking to effect an anti-join, for which there are three possibilities in MySQL:
Using NOT IN:
SELECT *
FROM petitions
WHERE id NOT IN (
SELECT petitionID
FROM petition_response
WHERE memberID = 14
)
Using NOT EXISTS:
SELECT *
FROM petitions p
WHERE NOT EXISTS (
SELECT *
FROM petition_response r
WHERE r.petitionID = p.id
AND r.memberID = 14
LIMIT 1
)
Using an OUTER JOIN:
SELECT p.*
FROM petitions p
LEFT OUTER JOIN petition_response r
ON r.petitionID = p.id AND r.memberID = 14
WHERE r.petitionID IS NULL
See them on sqlfiddle.
According to #Quassnoi's analysis:
Summary
MySQL can optimize all three methods to do a sort of NESTED LOOPS ANTI JOIN.
It will take each value from t_left and look it up in the index on t_right.value. In case of an index hit or an index miss, the corresponding predicate will immediately return FALSE or TRUE, respectively, and the decision to return the row from t_left or not will be made immediately without examining other rows in t_right.
However, these three methods generate three different plans which are executed by three different pieces of code. The code that executes EXISTS predicate is about 30% less efficient than those that execute index_subquery and LEFT JOIN optimized to use Not exists method.
That’s why the best way to search for missing values in MySQL is using a LEFT JOIN / IS NULL or NOT IN rather than NOT EXISTS.
$query = "
SELECT *
FROM petition_response pr
LEFT
JOIN petitions p
ON p.id = pr.id
WHERE pr.memberID = 14
AND p.id IS NULL
ORDER
BY pr.timestamp DESC;
";
I'm currently trying to join two tables with a left join:
--portal--
id_portal (index)
id_venue
name_portal
--access--
id_access (index)
id_event
id_portal
id_tickets
scan_access
'access' contains a number of ticket types per portal for each event. I need to combine these to get the sum total of the scan_access column for each portal but include the portals that have 'null' scan_access to come up with '0'. To achieve this I've used a left join:
SELECT portal.name_portal, SUM(access.scan_access) AS total_scan
FROM portal LEFT JOIN access ON portal.id_portal = access.id_portal
WHERE portal.id_venue = $venueId
GROUP BY portal.id_portal
ORDER BY portal.id_portal ASC
which means I get the following:
Portal 1 - Null
Portal 2 - 40
Portal 3 - 33
Portal 4 - Null
but I have an issue when I need to also get the above result when taking into account the event (id_event) because when I use the following:
SELECT portal.name_portal, SUM(access.scan_access) AS total_scan
FROM portal LEFT JOIN access ON portal.id_portal = access.id_portal
WHERE portal.id_venue = $venueId AND access.id_event = 20
GROUP BY portal.id_portal
ORDER BY portal.id_portal ASC
I get:
Portal 2 - 40
Portal 3 - 33
which makes sense as those are the only two rows that have an id_event value. But how can I take this col into account without losing the other portals? also, is there a way in sql to make the 'null' a zero when returning a result? (I can fix the null after with php but wanted to see if it was possible)
By putting access.id_event = 20 in your WHERE clause, you turn your LEFT JOIN into an INNER JOIN. Move access.id_event = 20 into your join criteria to preserve your LEFT JOIN. As #echo_me mentioned, you can use COALESCE() to get rid of your zeroes. I'd put it around the SUM(), instead of inside.
SELECT portal.name_portal, COALESCE( SUM(access.scan_access), 0 ) AS total_scan
FROM portal LEFT JOIN access ON portal.id_portal = access.id_portal AND access.id_event = 20
WHERE portal.id_venue = $venueId
GROUP BY portal.id_portal
ORDER BY portal.id_portal ASC
to convert NULL to 0 use this
COALESCE(col, 0)
in your example it will be
SUM(COALESCE(access.scan_access, 0)) AS total_scan