I have a table event_tblwith columns id,add_date,name,events;
and I want count all rows and the latest add_date count, how can I get that in one sql statement?
select count(1) as total
from event_tbl
union
select count(id) as latestCount from event_tbl where add_date=(select max(add_date)
from event_tbl);
but the result is :
------
total|
------
5499|
-----
611 |
what is correct way with efficiency?
I would suggest writing this as:
select count(*) as total, sum(add_date = maxad) as lastestCount
from event_tbl e cross join
(select max(add_date) as maxad from event_tbl) ee;
Related
Here I have this table:
Copies
nInv | Subject | LoanDate | BookCode |MemberCode|
1 |Storia |15/04/2019 00:00:00 |7844455544| 1 |
2 |Geografia |12/09/2020 00:00:00 |8004554785| 4 |
4 |Francese |17/05/2006 00:00:00 |8004894886| 3 |
5 |Matematica |17/06/2014 00:00:00 |8004575185| 3 |
I'm trying to find the value of the highest number of duplicates in the MemberCode column. So in this case I should get 3 as result, as its value appears two times in the table. Also, MemberCode is PK in another table, so ideally I should select all rows of the second table that match the MemberCode in both tables. For the second part I guess I should write something like SELECT * FROM Table2, Copies WHERE Copies.MemberCode = Table2.MemberCode but I'm missing out almost everything on the first part. Can you guys help me?
Use group by and limit:
select membercode, count(*) as num
from t
group by membercode
order by count(*) desc
limit 1;
SELECT MAX(counted) FROM
(SELECT COUNT(MemberCode) AS counted
FROM table_name GROUP BY MemberCode)
Using analytic functions, we can assign a rank to each member code based on its count. Then, we can figure out what its count is.
WITH cte AS (
SELECT t2.MemberCode, COUNT(*) AS cnt,
RANK() OVER (ORDER BY COUNT(*) DESC, t2.MemberCode) rnk
FROM Table2 t2
INNER JOIN Copies c ON c.MemberCode = t2.MemberCode
GROUP BY t2.MemberCode
)
SELECT cnt
FROM cte
WHERE rnk = 1;
Something like this
with top_dupe_member_cte as (
select top(1) MemberCode, Count(*)
from MemberTable
group by MemberCode
order by 2 desc)
select /* columns from your other table */
from OtherTable ot
join top_dupe_member_cte dmc on ot.MemberCode=dmc.MemberCode;
I have a table that has user_id and purchase_id. I want to filter the table so that only users with more than 2 purchases (i.e. there are more than 2 rows for that user in the table). I used count and group by, but it does not work in a way I want.
create view myview as
select user_Id, purchase_id, count(*) as count from mytable group by user_Id;
select user_id, purchase_id from myview where count >2;
But it gives me only users (only one user_id) that has more than 2 purchase and it does not give me all of their purchases. For example if the table looks like this:
user_id purchase_id
1 1212
1 1312
2 1232
1 1321
3 1545
3 4234
My query gives me this :
1 1212
3 1545
But I want this:
1 1212
1 1312
1 1321
3 1545
3 4234
change your last sql like this
select mt.user_id, mt.purchase_id
from myview mv
inner join mytable mt
on mt.user_id=mv.user_id where mv.count >5;
SELECT
*
FROM
mytable mt,
(SELECT user_id, count(*) AS purchase_count FROM mytable GROUP BY user_id) ct
WHERE
mt.user_id = ct.user_id AND ct.purchase_count > 5;
SELECT *
FROM MYTABLE
WHERE USER_ID IN (SELECT USER_ID
FROM MYTABLE
GROUP BY USER_ID
HAVING COUNT(*)>=2)
I tested in my netezza,it works. hopefully, it's also working in mysql
Try GROUP BY with HAVING comment.
SELECT user_Id, purchase_id
FROM mytable
GROUP BY user_Id
HAVING count( * ) >5
As far as I can tell you want to list the user id's and purchase id's of all users that have over 5 purchases.
In order to do this you could do a join on two queries.
For example:
SELECT tblLeft.user_id,
tblLeft.purchase_id
FROM myview tblLeft
JOIN (SELECT user_id,
Count(*) AS purchases
FROM myview
GROUP BY user_id
HAVING purchases > 1) tblRight
ON tblLeft.user_id = tblRight.user_id
The tblRight is essentially a table containing the user_id's of all users with over 5 purchases.
We then do a select (tblLeft) and join it on the tbl right, ensuring only customers with over 5 purchases remain.
I have a question: it's possible to create an count in count in sql:
my code is:
SELECT COUNT( DISTINCT p.id_participant ) as number
FROM participation p
INNER JOIN message m ON m.id_participation=p.id
AND p.id_event = 4
I want to add in first count another count from table winners with count (id_winner)
Help me please, Exist a solution?
You need to use the aggregate function SUM.
For example,
SQL> SELECT SUM(val)
2 FROM (SELECT Count(*) VAL
3 FROM emp
4 UNION
5 SELECT Count(*) VAL
6 FROM dept);
SUM(VAL)
----------
18
I have a table tbl_patient and I want to fetch last 2 visit of each patient in order to compare whether patient condition is improving or degrading.
tbl_patient
id | patient_ID | visit_ID | patient_result
1 | 1 | 1 | 5
2 | 2 | 1 | 6
3 | 2 | 3 | 7
4 | 1 | 2 | 3
5 | 2 | 3 | 2
6 | 1 | 3 | 9
I tried the query below to fetch the last visit of each patient as,
SELECT MAX(id), patient_result FROM `tbl_patient` GROUP BY `patient_ID`
Now i want to fetch the 2nd last visit of each patient with query but it give me error
(#1242 - Subquery returns more than 1 row)
SELECT id, patient_result FROM `tbl_patient` WHERE id <(SELECT MAX(id) FROM `tbl_patient` GROUP BY `patient_ID`) GROUP BY `patient_ID`
Where I'm wrong
select p1.patient_id, p2.maxid id1, max(p1.id) id2
from tbl_patient p1
join (select patient_id, max(id) maxid
from tbl_patient
group by patient_id) p2
on p1.patient_id = p2.patient_id and p1.id < p2.maxid
group by p1.patient_id
id11 is the ID of the last visit, id2 is the ID of the 2nd to last visit.
Your first query doesn't get the last visits, since it gives results 5 and 6 instead of 2 and 9.
You can try this query:
SELECT patient_ID,visit_ID,patient_result
FROM tbl_patient
where id in (
select max(id)
from tbl_patient
GROUP BY patient_ID)
union
SELECT patient_ID,visit_ID,patient_result
FROM tbl_patient
where id in (
select max(id)
from tbl_patient
where id not in (
select max(id)
from tbl_patient
GROUP BY patient_ID)
GROUP BY patient_ID)
order by 1,2
SELECT id, patient_result FROM `tbl_patient` t1
JOIN (SELECT MAX(id) as max, patient_ID FROM `tbl_patient` GROUP BY `patient_ID`) t2
ON t1.patient_ID = t2.patient_ID
WHERE id <max GROUP BY t1.`patient_ID`
There are a couple of approaches to getting the specified resultset returned in a single SQL statement.
Unfortunately, most of those approaches yield rather unwieldy statements.
The more elegant looking statements tend to come with poor (or unbearable) performance when dealing with large sets. And the statements that tend to have better performance are more un-elegant looking.
Three of the most common approaches make use of:
correlated subquery
inequality join (nearly a Cartesian product)
two passes over the data
Here's an approach that uses two passes over the data, using MySQL user variables, which basically emulates the analytic RANK() OVER(PARTITION ...) function available in other DBMS:
SELECT t.id
, t.patient_id
, t.visit_id
, t.patient_result
FROM (
SELECT p.id
, p.patient_id
, p.visit_id
, p.patient_result
, #rn := if(#prev_patient_id = patient_id, #rn + 1, 1) AS rn
, #prev_patient_id := patient_id AS prev_patient_id
FROM tbl_patients p
JOIN (SELECT #rn := 0, #prev_patient_id := NULL) i
ORDER BY p.patient_id DESC, p.id DESC
) t
WHERE t.rn <= 2
Note that this involves an inline view, which means there's going to be a pass over all the data in the table to create a "derived tabled". Then, the outer query will run against the derived table. So, this is essentially two passes over the data.
This query can be tweaked a bit to improve performance, by eliminating the duplicated value of the patient_id column returned by the inline view. But I show it as above, so we can better understand what is happening.
This approach can be rather expensive on large sets, but is generally MUCH more efficient than some of the other approaches.
Note also that this query will return a row for a patient_id if there is only one id value exists for that patient; it does not restrict the return to just those patients that have at least two rows.
It's also possible to get an equivalent resultset with a correlated subquery:
SELECT t.id
, t.patient_id
, t.visit_id
, t.patient_result
FROM tbl_patients t
WHERE ( SELECT COUNT(1) AS cnt
FROM tbl_patients p
WHERE p.patient_id = t.patient_id
AND p.id >= t.id
) <= 2
ORDER BY t.patient_id ASC, t.id ASC
Note that this is making use of a "dependent subquery", which basically means that for each row returned from t, MySQL is effectively running another query against the database. So, this will tend to be very expensive (in terms of elapsed time) on large sets.
As another approach, if there are relatively few id values for each patient, you might be able to get by with an inequality join:
SELECT t.id
, t.patient_id
, t.visit_id
, t.patient_result
FROM tbl_patients t
LEFT
JOIN tbl_patients p
ON p.patient_id = t.patient_id
AND t.id < p.id
GROUP
BY t.id
, t.patient_id
, t.visit_id
, t.patient_result
HAVING COUNT(1) <= 2
Note that this will create a nearly Cartesian product for each patient. For a limited number of id values for each patient, this won't be too bad. But if a patient has hundreds of id values, the intermediate result can be huge, on the order of (O)n**2.
Try this..
SELECT id, patient_result FROM tbl_patient AS tp WHERE id < ((SELECT MAX(id) FROM tbl_patient AS tp_max WHERE tp_max.patient_ID = tp.patient_ID) - 1) GROUP BY patient_ID
Why not use simply...
GROUP BY `patient_ID` DESC LIMIT 2
... and do the rest in the next step?
I already read (this), but couldn't figure out a way to implement it to my specific problem. I know SUM() is an aggregate function and it doesn't make sense not to use it as such, but in this specific case, I have to SUM() all of the results while maintaining every single row.
Here's the table:
--ID-- --amount--
1 23
2 11
3 8
4 7
I need to SUM() the amount, but keep every record, so the output should be like:
--ID-- --amount--
1 49
2 49
3 49
4 49
I had this query, but it only sums each row, not all results together:
SELECT
a.id,
SUM(b.amount)
FROM table1 as a
JOIN table1 as b ON a.id = b.id
GROUP BY id
Without the SUM() it would only return one single row, but I need to maintain all ID's...
Note: Yes this is a pretty basic example and I could use php to do this here,but obviously the table is bigger and has more rows and columns, but that's not the point.
SELECT a.id, b.amount
FROM table1 a
CROSS JOIN
(
SELECT SUM(amount) amount FROM table1
) b
You need to perform a cartesian join of the value of the sum of every row in the table to each id. Since there is only one result of the subselect (49), it basically just gets tacked onto each id.
With MS SQL you can use OVER()
select id, SUM(amount) OVER()
from table1;
select id, SUM(amount) OVER()
from (
select 1 as id, 23 as amount
union all
select 2 as id, 11 as amount
union all
select 3 as id, 8 as amount
union all
select 4 as id, 7 as amount
) A
--- OVER PARTITION ID
PARTITION BY which is very useful when you want to do SUM() per MONTH for example or do quarterly reports sales or yearly...
(Note needs distinct it is doing for all rows)
select distinct id, SUM(amount) OVER(PARTITION BY id) as [SUM_forPARTITION]
from (
select 1 as id, 23 as amount
union all
select 1 as id, 23 as amount
union all
select 2 as id, 11 as amount
union all
select 2 as id, 11 as amount
union all
select 3 as id, 8 as amount
union all
select 4 as id, 7 as amount
) OverPARTITIONID
Join the original table to the sum with a subquery:
SELECT * FROM table1, (SELECT SUM(amount) FROM table1 AS amount) t
This does just one sum() query, so it should perform OK:
SELECT a.id, b.amount
FROM table1 a
cross join (SELECT SUM(amount) as amount FROM table1 AS amount) b
in case someone else has the same problem and without joining we can do the following
select *
,totcalaccepted=(select sum(s.acceptedamount) from cteresult s)
, totalpay=(select sum(s.payvalue) from cteresult s)
from cteresult t
end
Using Full Join -
case when you need sum of amount field from tableB and all data from tableA on behalf of id match.
SELECT a.amount, b.* FROM tableB b
full join (
select id ,SUM(amount) as amount FROM tableA
where id = '1' group by id
) a
on a.id = b.id where a.id ='1' or b.id = '1' limit 1;