I want to find ranking and then update their rank column according to their id.
My data is as follows (Table Member).
MEMBER_ID | LOAN_AMOUNT | Rank
1 | 2,000.00 | 0
2 | 1,000.00 | 0
3 | 4,000.00 | 0
4 | 1,000.00 | 0
Now I want to find their ranking and update rank column according to it.
My general query is something like it:
UPDATE
Member AS dest,
(
SELECT RANK() OVER(ORDER BY t.loan_amount DESC) as [rank],
t.memeber_id,t.loan_amount
FROM Member
) AS src
SET
dest.rank = src.rank
INNER JOIN dest.memeber_id = src.memeber_id
Is there any faster way to update my table?
In mysql the update join sintax should be
UPDATE
Member AS dest
INNER JOIN
(
SELECT RANK() OVER(ORDER BY t.loan_amount DESC) as [rank],
t.memeber_id,t.loan_amount
FROM Member
) src ON dest.memeber_id = src.memeber_id
SET dest.rank = src.rank
anyway you should avoid store data easly calcuated on fly .. in the same time you perform the select can easly obtain also the rank()
Related
Ive got this query and I want to get all names from those clients that have the highest price of a day.
If multiple clients exist having the same max price, they shall be selected too.
I managed to get the customers with max price grouped by date but I dont think it gives me both customers if they have the same max value on the same day.
The names should be distinct.
The output needs to be as follows:
| Name (asc) |
------------------
| customer name |
| customer name |
| ...... |
The Orders table looks as follows:
|Client|Price|Orderdate |
------------------------
|1 |100.0|2010.01.10|
|... |... | ..... |
and the Client table:
|Client_NR|Name |
-----------------------
|1 |customer#001|
|2 |customer#002|
select distinct k1.NAME from Orders a LEFT JOIN Order b on a.Orderdate = b.Orderdate
JOIN Client k1 on k1.Client_NR = a.Client
where a.Price IN
(SELECT MAX(a.Price) from Order a group by Orderdate)
order by NAME asc
I presume my error lies within the Join Client line but I just cant figure it out.
Ive tried to use a.price = b.price in the first join but the test would fail.
Any advise is highly appreciated.
WITH cte AS ( SELECT Client.Name,
RANK() OVER (PARTITION BY Orders.Orderdate
ORDER BY Orders.Price DESC) rnk
FROM Client
JOIN Orders ON Client.Client_NR = Orders.Client )
SELECT Name
FROM cte
WHERE rnk = 1
ORDER BY Name
I want to fetch data from two table and apply arithmetic operation on the column.
This is wha I tried :
String sql = "SELECT SUM(S.san_recover-C.amount) as total
FROM sanction S
LEFT JOIN collection C ON S.client_id = C.client_id
WHERE S.client_id=?";
This code is working only when there is value in both tables, but if there is no value in one of two tables there is no result.
SELECT SUM(S.san_recover - C.amount) as total
FROM sanction S
LEFT JOIN collection C ON S.client_id = C.client_id
WHERE S.client_id = ?
The problem with your query lies in the SUM() function. When the left join does not bring back records, then c.amount is NULL. When substracting NULL from something, you get a NULL result, which then propagates across the computation, and you end up with a NULL result for the SUM().
You probably want COALESCE(), like so:
SELECT SUM(S.san_recover - COALESCE(C.amount, 0)) as total
FROM sanction S
LEFT JOIN collection C ON S.client_id = C.client_id
WHERE S.client_id = ?
Where there is a possibility that a client may exist in one table but no another a full join would be appropriate but since mysql does not have such a thing then a union in a sub query will do
drop table if exists sanctions,collections;
create table sanctions(client_id int, amount int);
create table collections(client_id int, amount int);
insert into sanctions values
(1,10),(1,10),(2,10);
insert into collections values
(1,5),(3,10);
Select sum(Samount - camount)
From
(Select sum(amount) Samount, 0 as camount from sanctions where client_id =3
Union all
Select 0,sum(amount) as camount from collections where client_id =3
) s
;
+------------------------+
| sum(Samount - camount) |
+------------------------+
| -10 |
+------------------------+
1 row in set (0.00 sec)
If you want to do this for all clients
Select client_id,sum(Samount - camount) net
From
(Select client_id,sum(amount) Samount, 0 as camount from sanctions group by client_id
Union all
Select client_id,0,sum(amount) as camount from collections group by client_id
) s
group by client_id
;
+-----------+------+
| client_id | net |
+-----------+------+
| 1 | 15 |
| 2 | 10 |
| 3 | -10 |
+-----------+------+
3 rows in set (0.00 sec)
I've seen many questions along this issue, but can't get this to work.
I want to UPDATE multiple columns in a table (but will start with one) based upon a calculated value from the same table.
It is a list of transactions per customer, per month.
TransID | Cust | Month | Value | PastValue | FutureValue
1 | 1 | 2018-01-01 | 45 |
2 | 1 | 2018-02-01 | 0 |
3 | 1 | 2018-03-01 | 35 |
4 | 1 | 2018-04-01 | 80 |
.
UPDATE tbl_transaction a
SET PrevMnthValue =
(SELECT COUNT(TransactionID) FROM tbl_transaction b WHERE b.Cust=a.Cust AND b.Month<a.Month)
But we get the dreaded 'Can't update a table using a where with a subquery of the same table).
I've tried to nest the subquery as this has been touted as a workaround:
UPDATE tbl_transactions a
SET
PastValue =
(
SELECT CNT FROM
(
SELECT
COUNT(TransactionID) AS CNT
FROM tbl_transactions b
WHERE
b.CustomerRef=a.CustomerRef AND b.Month<a.Month
) x
),
FutureValue =
(
SELECT CNT FROM
(
SELECT
COUNT(TransactionID) AS CNT
FROM tbl_transactions b
WHERE
b.CustomerRef=a.CustomerRef AND b.Month>a.Month
) x
)
But I get an UNKNOWN a.CustomerRef in WHERE clause. Where am I going wrong?
You can't update and read from one table at the same time.
MySQL documentation tell about it
You cannot update a table and select from the same table in a subquery.
At first you must select necessary data and save them to somewhere, for example to temporary table
CREATE TEMPORARY TABLE IF NOT EXISTS `temp` AS (
SELECT
COUNT(`TransactionID`) AS CNT,
`CustomerRef`,
`Month`
FROM `tbl_transactions`
GROUP BY `Custom,erRef`, `Month`
);
After it, you can use JOIN statement for update table
UPDATE `tbl_transactions` RIGTH
JOIN `temp` ON `temp`.`CustomerRef` = `tbl_transactions`.`CustomerRef`
AND `temp`.`Month` < `tbl_transactions`.`Month`
SET `tbl_transactions`.`PastValue` = `temp`.`cnt`
UPDATED: if you want to update several columns by different condition you can combine temporary table, UPDATE + RIGHT JOIN and CASE statement. For example:
UPDATE `tbl_transactions`
RIGTH JOIN `temp` ON `temp`.`CustomerRef` = `tbl_transactions`.`CustomerRef`
SET `tbl_transactions`.`PastValue` = CASE
WHEN `temp`.`Month` < `tbl_transactions`.`Month` THEN `temp`.`cnt`
ELSE `tbl_transactions`.`PastValue`
END,
`tbl_transactions`.`FutureValue` = CASE
WHEN `temp`.`Month` > `tbl_transactions`.`Month` THEN `temp`.`cnt`
ELSE `tbl_transactions`.`FutureValue`
END
You can try below
UPDATE tbl_transactions a
Join
( SELECT CustomerRef,COUNT(TransactionID) AS CNT FROM tbl_transactions b
group by CustomerRef)x
SET PastValue = CNT
WHERE x.CustomerRef=a.CustomerRef AND x.Month<a.Month
I have a table like this:
timesent |nr | value
2018-10-31 05:23:06 | 4 | Value 3
2018-10-31 05:20:19 | 4 | Value 2
2018-10-31 05:19:35 | 4 | Value 1
2018-10-31 04:55:56 | 3 | Value 2
2018-10-31 03:05:15 | 3 | Value 1
2018-10-31 01:31:49 | 2 | Value 1
2018-10-30 04:11:16 | 1 | Value 1
At the moment, my select looks like this:
SELECT * FROM values WHERE ORDER BY timesent DESC
I want to do an sql-select statement which gives me back only the most recent value of each "nr".
My skills are not good enough to translate that into a sql-statement. I don´t even know what I should google for.
Values is a Reserved Keyword in MySQL. Consider changing your table name to something else; otherwise you will have to use backticks around it
There are various ways to achieve the result for your problem. One way is to do a "Self-Left-Join" on nr (field on which you want to get the maximum timesent value row only).
SELECT v1.*
FROM `values` AS v1
LEFT JOIN `values` AS v2
ON v1.nr = v2.nr AND
v1.timesent < v2.timesent
WHERE v2.nr IS NULL
For MySQL version >= 8.0.2, you can use Window Functions. We will determine Row_Number() for each row over a partition of nr, with timesent in Descending order (Highest timesent value will have row number = 1). Then, use this result-set in a Derived Table and consider only those rows, where row number is equal to 1.
SELECT dt.timesent,
dt.nr,
dt.value
FROM
(
SELECT v.timesent, v.nr, v.value,
ROW_NUMBER() OVER (PARTITION BY v.nr
ORDER BY v.timesent DESC) AS row_num
FROM `values` AS v
) AS dt
WHERE dt.row_num = 1
Yet, another approach is to get the maximum value of timesent for a nr group in a Derived Table. Now join this result-set to the main table, so that only the rows corresponding to max value appear:
SELECT v.timesent,
v.nr,
v.value
FROM
`values` AS v
JOIN
(
SELECT nr, MAX(timesent) AS max_timesent
FROM `values`
GROUP BY nr
) AS dt ON dt.nr = v.nr AND
dt.max_timesent = v.timesent
I'd like to construct a single query (or as few as possible) to group a data set. So given a number of buckets, I'd like to return results based on a specific column.
So given a column called score which is a double which contains:
90.00
91.00
94.00
96.00
98.00
99.00
I'd like to be able to use a GROUP BY clause with a function like:
SELECT MIN(score), MAX(score), SUM(score) FROM table GROUP BY BUCKETS(score, 3)
Ideally this would return 3 rows (grouping the results into 3 buckets with as close to equal count in each group as is possible):
90.00, 91.00, 181.00
94.00, 96.00, 190.00
98.00, 99.00, 197.00
Is there some function that would do this? I'd like to avoid returning all the rows and figuring out the bucket segments myself.
Dave
create table test (
id int not null auto_increment primary key,
val decimal(4,2)
) engine = myisam;
insert into test (val) values
(90.00),
(91.00),
(94.00),
(96.00),
(98.00),
(99.00);
select min(val) as lower,max(val) as higher,sum(val) as total from (
select id,val,#row:=#row+1 as row
from test,(select #row:=0) as r order by id
) as t
group by ceil(row/2)
+-------+--------+--------+
| lower | higher | total |
+-------+--------+--------+
| 90.00 | 91.00 | 181.00 |
| 94.00 | 96.00 | 190.00 |
| 98.00 | 99.00 | 197.00 |
+-------+--------+--------+
3 rows in set (0.00 sec)
Unluckily mysql doesn't have analytical function like rownum(), so you have to use some variable to emulate it. Once you do it, you can simply use ceil() function in order to group every tot rows as you like. Hope that it helps despite my english.
set #r = (select count(*) from test);
select min(val) as lower,max(val) as higher,sum(val) as total from (
select id,val,#row:=#row+1 as row
from test,(select #row:=0) as r order by id
) as t
group by ceil(row/ceil(#r/3))
or, with a single query
select min(val) as lower,max(val) as higher,sum(val) as total from (
select id,val,#row:=#row+1 as row,tot
from test,(select count(*) as tot from test) as t2,(select #row:=0) as r order by id
) as t
group by ceil(row/ceil(tot/3))