I'm trying to find some records based on the tags they have. In order to find out which tags a record has I add them to the result using a subquery. To find out which results should be returned I added a having statement at the end of the query. But something tells me this is not the best way. Is there any other way to do it?
Here is the query that takes too much time to execute.
SELECT c.id,c.currentBalance,
(SELECT running_balance from vrCorporateLedger WHERE company_id=c.id
ORDER by id DESC LIMIT 1) AS ledgerBalance
FROM company AS c
WHERE c.vrCorporate='YES'
AND c.deleted_at IS NULL
HAVING currentBalance > ledgerBalance
This should do the trick:
SELECT c.id,c.currentBalance,
vrcl.running_balance ledgerBalance
FROM company AS c
INNER JOIN vrCorporateLedger vrcl
ON vrcl.id = c.company_id
WHERE c.vrCorporate='YES'
AND c.deleted_at IS NULL
AND currentBalance > vrcl.running_balance
Related
I'm working on a project involving words and its translations. One of the queries a translator must task frequently (once every 10 sec or so) is:
SELECT * FROM pwords p
LEFT JOIN words w ON p.id = w.wordid
WHERE w.code IS NULL
OR (w.code <> "USER1" AND w.code <> "USER2")
ORDER BY rand() LIMIT 10
To receive a word to be translated, which the user has not translated already. In this case we want to disallow words input by USER2
The pwords table has around 66k entries and the words table has around 55k entries.
This query takes about 500 seconds to complete, whereas if I remove the IS NULL the query takes 0.0245 ms. My question here is: is there a way to optimize this query? I really need to squeeze the numbers.
The scenario is: USER1 does not want any database entries from USER2 in the words table. It does not want it's own database entries from the same table. Therefore I need to have the IS NULL or a similar method to get entries from all users except USER1 and USER2, either from other users or NULL entries.
tl;dr So my question is: is there a way to make this query run faster? Is "IS NULL" optimizable?
Any and all help is greatly appreciated.
You can try using subquery in order to filter the rows (use WHERE statement) as soon as possible:
SELECT *
FROM pwords p
LEFT JOIN
(SELECT *
FROM words w
WHERE (w.code <> "USER1" AND w.code <> "USER2")) subq
ON p.id = subq.wordid
WHERE w.code IS NULL
ORDER BY rand() LIMIT 10
another (and maybe a more efficient option) is using NOT EXISTS statement:
SELECT *
FROM pwords p
WHERE NOT EXISTS
(SELECT *
FROM words w
WHERE p.id=w.wordid AND (w.code <> "USER1" AND w.code <> "USER2"))
ORDER BY rand() LIMIT 10
SELECT LM.user_id,LM.users_lineup_id, min( LM.total_score ) AS total_score
FROM vi_lineup_master LM JOIN
vi_contest AS C
ON C.contest_unique_id = LM.contest_unique_id join
(SELECT min( total_score ) as total_score
FROM vi_lineup_master
GROUP BY group_unique_id
) as preq
ON LM.total_score = preq.total_score
WHERE LM.contest_unique_id = 'iledhSBDO' AND
C.league_contest_type = 1
GROUP BY group_unique_id
Above query is to find the loser per group of game, query return accurate result but its not responding with large data. How can I optimize this?
You can try to move your JOINs to subqueries. Also, you should pay attention on your "wrong" GROUP BY usage on the outer query. In Mysql you can group by some columns and select others not specified in the group clause without any aggregation function, but the database can't ensure what data it will return to you. For the sake of consistency of your application, wrap them in an aggregation function.
Check if this one helps:
SELECT
MIN(LM.user_id) AS user_id,
MIN(LM.users_lineup_id) AS users_lineup_id,
MIN(LM.total_score) AS total_score
FROM vi_lineup_master LM
WHERE 1=1
-- check if this "contest_unique_id" is equals
-- to 'iledhSBDO' for a "league_contest_type" valued 1
AND LM.contest_unique_id IN
(
SELECT C.contest_unique_id
FROM vi_contest AS C
WHERE 1=1
AND C.contest_unique_id = 'iledhSBDO'
AND C.league_contest_type = 1
)
-- check if this "total_score" is one of the
-- "min(total_score)" from each "group_unique_id"
AND LM.total_score IN
(
SELECT MIN(total_score)
FROM vi_lineup_master
GROUP BY group_unique_id
)
GROUP BY LM.group_unique_id
;
Also, some pieces of this query may seem redundant, but it's because I did not want to change the filters you wrote, just moved them.
Also, your query logic seems a bit strange to me, based on the tables/columns names and how you wrote it... please, check the comments in my query which reflects what I understood of your implementation.
Hope it helps.
Take the following:
SELECT
Count(a.record_id) AS newrecruits
,a.studyrecord_id
FROM
visits AS a
INNER JOIN
(
SELECT
record_id
, MAX(modtime) AS latest
FROM
visits
GROUP BY
record_id
) AS b
ON (a.record_id = b.record_id) AND (a.modtime = b.latest)
WHERE (((a.visit_type_id)=1))
GROUP BY a.studyrecord_id;
I want to amend the COUNT part to display a zero if there are no records since I assume COUNT will evaluate to Null.
I have tried the following but still get no results:
IIF(ISNULL(COUNT(a.record_id)),0,COUNT(a.record_id)) AS newrecruits
Is this an issue because the join is on record_id? I tried changing the INNER to LEFT but also received no results.
Q
How do I get the above to evaluate to zero if there are no records matching the criteria?
Edit:
To give a little detail to the reasoning.
The studies table contains a field called 'original_recruits' based on activity before use of the database.
The visits tables tracks new_recruits (Count of records for each study).
I combine these in another query (original_recruits + new_recruits)- If there have been no new recruits I still need to display the original_recruits so if there are no records I need it to evalulate to zero instead of null so the final sum still works.
It seems like you want to count records by StudyRecords.
If you need a count of zero when you have no records, you need to join to a table named StudyRecords.
Did you have one? Else this is a nonsense to ask for rows when you don't have rows!
Let's suppose the StudyRecords exists, then the query should look like something like this :
SELECT
Count(a.record_id) AS newrecruits -- a.record_id will be null if there is zero count for a studyrecord, else will contain the id
sr.Id
FROM
visits AS a
INNER JOIN
(
SELECT
record_id
, MAX(modtime) AS latest
FROM
visits
GROUP BY
record_id
) AS b
ON (a.record_id = b.record_id) AND (a.modtime = b.latest)
LEFT OUTER JOIN studyrecord sr
ON sr.Id = a.studyrecord_id
WHERE a.visit_type_id = 1
GROUP BY sr.Id
I solved the problem by amending the final query where I display the result of combining the original and new recruits to include the IIF there.
SELECT
a.*
, IIF(IsNull([totalrecruits]),consents,totalrecruits)/a.target AS prog
, IIf(IsNull([totalrecruits]),consents,totalrecruits) AS trecruits
FROM
q_latest_studies AS a
LEFT JOIN q_totalrecruitment AS b
ON a.studyrecord_id=b.studyrecord_id
;
I'm sure this will be quite simple for some one clued up in SQL but I think it needs a sub query or something. I have a table which basically has a load of order numbers in it and a reply column from an XML API. Either FAIL or SUCCESS.
A brand new row is inserted into the DB after every request. So there may be 5 FAILS for one order number, and on the 6th attempt a record is inserted saying SUCCESS.
How can I put out order numbers that ONLY have a FAIL status next to them?
This will allow me to figure out what records need looking into that continuously fail in the API request.
Try this, by grouping your orders with primary key (order_id)
SELECT * FROM
(
SELECT GROUP_CONCAT(status) as status_combined, order_id
FROM orders
GROUP BY order_id
) AS order_tmp
WHERE status_combined NOT LIKE '%SUCCESS%'
Edit (As per asker comments)
SELECT * FROM
(
SELECT GROUP_CONCAT(status) as status_combined, order_id
FROM orders
JOIN certificates ON certificates.Ordernumber = orders.OrderNumber
GROUP BY order_id
) AS order_tmp
WHERE status_combined NOT LIKE '%SUCCESS%'
please make sure you need to join based on "Ordernumber" or "order_id"
Try this
select m.*
from Main m
join Transactiontable tt
on m.orderid = tt.orderid
group by tt.status , m.orderid
having count(case when tt.status = "failed") = count(tt.status)
You can use simple sql query using a where clause:
select *
from some_table
where Column_From_some_table_has_value = your_particular_value
thats enough.
You can have a look at How to use where clause in sql
Thanks
This is probably the cleanest way to do it:
select *
from mytable
where id in (
select id
from mytable
group by id
having sum(status = 'SUCCESS') = 0)
I'm not a fan of #Minesh's answer because it uses both an aggregate function and the LIKE operator. Both of those can cause performance issues since there won't be any indexes to help the query out with the difficult part of the work. The LIKE clause particularly is a lot of work for the database since it will need to scan every result.
I'm more familiar with SQL Server, but this should work well for you:
SELECT *
FROM Orders
WHERE OrderNumber NOT IN (
SELECT OrderNumber
FROM Orders
WHERE Status = 'SUCCESS')
AND OrderNumber NOT IN (
SELECT OrderNumber
FROM Certificates
WHERE OrderStatus = 'CANCELLED')
In the following query, I show the latest status of the sale (by stage, in this case the number 3). The query is based on a subquery in the status history of the sale:
SELECT v.id_sale,
IFNULL((
SELECT (CASE WHEN IFNULL( vec.description, '' ) = ''
THEN ve.name
ELSE vec.description
END)
FROM t_record veh
INNER JOIN t_state_campaign vec ON vec.id_state_campaign = veh.id_state_campaign
INNER JOIN t_state ve ON ve.id_state = vec.id_state
WHERE veh.id_sale = v.id_sale
AND vec.id_stage = 3
ORDER BY veh.id_record DESC
LIMIT 1
), 'x') sale_state_3
FROM t_sale v
INNER JOIN t_quarters sd ON v.id_quarters = sd.id_quarters
WHERE 1 =1
AND v.flag =1
AND v.id_quarters =4
AND EXISTS (
SELECT '1'
FROM t_record
WHERE id_sale = v.id_sale
LIMIT 1
)
the query delay 0.0057seg and show 1011 records.
Because I have to filter the sales by the name of the state as it would have to repeat the subquery in a where clause, I have decided to change the same query using joins. In this case, I'm using the MAX function to obtain the latest status:
SELECT
v.id_sale,
IFNULL(veh3.State3,'x') AS sale_state_3
FROM t_sale v
INNER JOIN t_quarters sd ON v.id_quarters = sd.id_quarters
LEFT JOIN (
SELECT veh.id_sale,
(CASE WHEN IFNULL(vec.description,'') = ''
THEN ve.name
ELSE vec.description END) AS State3
FROM t_record veh
INNER JOIN (
SELECT id_sale, MAX(id_record) AS max_rating
FROM(
SELECT veh.id_sale, id_record
FROM t_record veh
INNER JOIN t_state_campaign vec ON vec.id_state_campaign = veh.id_state_campaign AND vec.id_stage = 3
) m
GROUP BY id_sale
) x ON x.max_rating = veh.id_record
INNER JOIN t_state_campaign vec ON vec.id_state_campaign = veh.id_state_campaign
INNER JOIN t_state ve ON ve.id_state = vec.id_state
) veh3 ON veh3.id_sale = v.id_sale
WHERE v.flag = 1
AND v.id_quarters = 4
This query shows the same results (1011). But the problem is it takes 0.0753 sec
Reviewing the possibilities I have found the factor that makes the difference in the speed of the query:
AND EXISTS (
SELECT '1'
FROM t_record
WHERE id_sale = v.id_sale
LIMIT 1
)
If I remove this clause, both queries the same time delay... Why it works better? Is there any way to use this clause in the joins? I hope your help.
EDIT
I will show the results of EXPLAIN for each query respectively:
q1:
q2:
Interesting, so that little statement basically determines if there is a match between t_record.id_sale and t_sale.id_sale.
Why is this making your query run faster? Because Where statements applied prior to subSelects in the select statement, so if there is no record to go with the sale, then it doesn't bother processing the subSelect. Which is netting you some time. So that's why it works better.
Is it going to work in your join syntax? I don't really know without having your tables to test against but you can always just apply it to the end and find out. Add the keyword EXPLAIN to the beginning of your query and you will get a plan of execution which will help you optimize things. Probably the best way to get better results in your join syntax is to add some indexes to your tables.
But I ask you, is this even necessary? You have a query returning in <8 hundredths of a second. Unless this query is getting ran thousands of times an hour, this is not really taxing your DB at all and your time is probably better spent making improvements elsewhere in your application.