For example, I have the table with the next columns: id, fk_id, date, order. How can I select something like this:
select
id
from cards
where fk_id = pId
and date = pDate;
but I need to get only the row with the highest order value. How can I do that? Thank you.
UPD1: First of all - thank you for your answers. Column names are completely different in the real table, it's just dummy names for question. Is there any way to do so that select by joining tha table with itself?
You would use the aggregating function KEEP DENSE_RANK FIRST for that:
select
MIN(id) KEEP (DENSE_RANK FIRST ORDER BY "order" desc)
from cards
where fk_id = pId
and "date" = pDate;
First of all, do not use the words "order" and "date" for column names. Both are reserved words in SQL (ORDER BY ... clause, DATE is a data type). So in my example I am going to use "myorder" and "mydate" instead...
I assume your example as purely hypothetical because with the selected column names it would most likely not work on any SQL database, anyway.
In Oracle database you could try this:
select ID from
( select ID, row_number() over (partition by ID order by MYORDER) as RN
from CARDS where FK_ID = PID and MYDATE = PDATE)
where RN = 1
However, your select only has one column, ID. So if you simply do
select distinct ID from CARDS
you will get exactly the same result...
Something like this:
SELECT id
FROM cards
WHERE orderValue = (SELCT MAX(orderValue)
FROM cards
WHERE fk_id = pId
AND date = pDate)
AND fk_id = pId
AND date = pDate;
This is fairly efficient.
You can try something like this:
select
id
from cards
where fk_id = pId
and date = pDate
order by desc
limit 1;
Related
I have table as below:
I want write a sql query to get output as below:
the query should select all the records from the table but, when multiple records have same Id column value then it should take only one record having latest Date.
E.g., Here Rudolf id 1211 is present three times in input---in output only one Rudolf record having date 06-12-2010 is selected. same thing with James.
I tried to write a query but it was not succssful. So, please help me to form a query string in sql.
Thanks in advance
You can partition your data over Date Desc and get the first row of each partition
SELECT A.Id, A.Name, A.Place, A.Date FROM (
SELECT
*,
ROW_NUMBER() OVER (PARTITION BY Id ORDER BY Date DESC) AS rn
FROM [Table]
) A WHERE A.rn = 1
you can use WITH TIES
select top 1 PERCENT WITH TIES * from t
order by (row_number() over(partition by id order by date desc))
https://dbfiddle.uk/?rdbms=sqlserver_2017&fiddle=280b7412b5c0c04c208f2914b44c7ce3
As i can see from your example, duplicate rows differ only in Date. If it's a case, then simple GROUP BY with MAX aggregate function will do the job for you.
SELECT Id, Name, Place, MAX(Date)
FROM [TABLE_NAME]
GROUP BY Id, Name, Place
Here is working example: http://sqlfiddle.com/#!18/7025e/2
Select id, name , max(modify_time)
from customer
group by id, name
but I get all records.
Order by modify_time desc and use row_number to number the row for id,name combination.Then select each combination with row_number = 1
select id,modify_time,name
from (
select id,modify_time,name,row_number() over(partition by id order by modify_time desc) as r_no
from customer
) a
where a.r_no=1
Ids are unique, which means grouping them by the id, will result in the same table.
My suggestion would be, to order the table by "modify_time" descending and limit the result to 1 (Maybe something like the following):
Select id, name modify_time from customer ORDER BY modify_time DESC limit 1
The reason you are getting the whole table as a result is because you are grouping by id AND name. That means every unique combination of id and name is returned. And since all names per id are different, the whole table is returned.
If you want the last modification per id (or name) you should only group by id (or name respectively).
I have a postgresql table wherein I have few fields such as id and date. I need to find the max date for that id and show the same into a new field for all the ids. SQLFiddle site was not responding so I have an example in the excel. Here is the screenshot of the data and the output for the table.
You could use the windowing variant of max:
SELECT id, date, MAX(date) OVER (PARTITION BY id)
FROM mytable
Something like this might work:
WITH maxdts AS (
SELECT id, max(dt) maxdt FROM table GROUP BY id
)
SELECT id, date, maxdt FROM table t, maxdts m WHERE t.id = m.id;
Keep in mind without more information that this could be a horribly inefficient query, but it will get you what you need.
I am trying to get the last registration date of a course, but I want to know the id of thar record. As MAX is a function, I must use group by id, which I do not want, because the result is very different (From only one record to each record per id).
Which is the way to manage a query like this?:
SELECT id, MAX(registration_date) AS registration_date
FROM courses;
Because it gives an error and I must do this to avoid it:
SELECT id, MAX(registration_date) AS registration_date
FROM courses
GROUP BY id;
And I do not want the result of the last one.
You could use the rank() window function for that:
SELECT id
FROM (SELECT id, RANK() OVER (ORDER BY registration_date DESC) AS rk
FROM courses)
WHERE rk = 1
One method is to use a sub query like this:
select *
from [dbo].[Courses]
where registration_date =
(select max(registration_date)
from [dbo].[Courses])
but with only a date to match this may return more than one record.
If possible, include more fields in the where clause to narrow it down.
Very simple basic SQL question here.
I have this table:
Row Id __________Hour__Minute__City_Search
1___1409346767__23____24_____Balears (Illes)
2___1409346767__23____13_____Albacete
3___1409345729__23____7______Balears (Illes)
4___1409345729__23____3______Balears (Illes)
5___1409345729__22____56_____Balears (Illes)
What I want to get is only one distinct row by ID and select the last City_Search made by the same Id.
So, in this case, the result would be:
Row Id __________Hour__Minute__City_Search
1___1409346767__23____24_____Balears (Illes)
3___1409345729__23____7______Balears (Illes)
What's the easier way to do it?
Obviously I don't want to delete any data just query it.
Thanks for your time.
SELECT Row,
Id,
Hour,
Minute,
City_Search
FROM Table T
JOIN
(
SELECT MIN(Row) AS Row,
ID
FROM Table
GROUP BY ID
) AS M
ON M.Row = T.Row
AND M.ID = T.ID
Can you change hour/minute to a timestamp?
What you want in this case is to first select what uniquely identifies your row:
Select id, max(time) from [table] group by id
Then use that query to add the data to it.
SELECT id,city search, time
FROM (SELECT id, max(time) as lasttime FROM [table] GROUP BY id) as Tkey
INNER JOIN [table] as tdata
ON tkey.id = tdata.id AND tkey.lasttime = tdata.time
That should do it.
two options to do it without join...
use Row_Number function to find the last one
Select * FROM
(Select *,
row_number() over(Partition BY ID Order BY Hour desc Minute Desc) as RNB
from table)
Where RNB=1
Manipulate the string and using simple Max function
Select ID,Right(MAX(Concat(Hour,Minute,RPAD(Searc,20,''))),20)
From Table
Group by ID
avoiding Joins is usually much faster...
Hope this helps