I have a table called service_t,it has a column effective_dt which is populated with unix timestamp. I need find all rows with max effective_dt but the effective_dt must be less than a given value. I have the following sql but I don’t think it’s efficient:
Select *
from service_t t1
where t1.effective_dt <= :given_value
and t1.effective_dt = (select max(effective_dt)
from service_t t2
where t2.effective_dt <= :given_value
and t1.id = t2.id)
Is this efficient or any other good ways? Thanks!
Using analytic functions is probably more efficient:
Select * from (
select t1.*,
dense_rank() over (partition by id order by effective_dt desc) rn
from service_t t1
where t1.effective_dt <= :given_value)
where rn = 1
Related
I have one table. From that I need to get latest "Date" for each "id". I wrote query for One id. But I don't know how to apply for multiple ids.(I mean for each id)
My query for one id is (say table name is tt):
select * from (
SELECT DISTINCT id ,date FROM tt
WHERE Trim(id) ='1000082'
ORDER BY date desc
) where rownum<=1;
If you have just two columns, aggregation is good enough:
select id, max(date) max_date
from mytable
group by id
If you have more columns and you want the entire row that has the latest date for each id, then one option uses a correlated subquery for filtering:
select t.*
from mytable t
where t.date = (select max(t1.date) from mytable t1 where t1.id = t.id)
Or you can use window functions, if your database supports them:
select *
from (select t.*, row_number() over(partition by id order by date desc) rn from mytable t) t
where rn = 1
I have a table with schema (id, date, value, source, ticker). I wanted to get record having highest ID group by date in sql server
Example Data
ID|date|value|source|ticker
3|10-Dec-2017|10|a|b
1|10-Dec-2017|11|p|q
Below query works in Sqlite. Do we know if I can do same with SqlServer
select max(id), date, value, source, ticker from table group by date
Expected return:-
ID|date|value|source|ticker
3|10-Dec-2017|10|a|b
Also how I can do same operation on UNION of 2 tables with same schema.
You can use subquery :
select t.*
from table t
where id = (select max(t1.id) from table t1 where t1.date = t.date);
However, you can also use row_number() function :
select top (1) with ties *
from table t
order by row_number() over (partition by [date] order by id desc);
You can also do it like below :
select t1.* from table1 t1
join (
select max(id) as id, [date] from table1
group by [date]
) as t2 on t1.id = t2.id
SQL HERE
I want to find out a rows which have maximum date by product,
I want to find out a maximum date of rows by product_id
I have tried a DISTINCT but can't succeed!
One canonical way of doing this is to use a subquery to identify the records corresponding to the maximum dates for each product ID, and then restrict the original table via an INNER JOIN.
SELECT t1.*
FROM yourTable t1
INNER JOIN
(
SELECT PRODUCT_ID, MAX(DATE) AS DATE
FROM yourTable
GROUP BY PRODUCT_ID
) t2
ON t1.PRODUCT_ID = t2.PRODUCT_ID AND
t1.DATE = t2.DATE
Another way to do this would be via a window function.
select * from (
SELECT *, row_number() over (partition by Product_ID order by date desc) r
FROM table
) T
WHERE T.r=1
Need to find in databse max value, but then i need read other values in columns.
Can this be done with one SQL command or I have to use this two commands?
SELECT MAX(id) FROM Table;
SELECT * FROM Table WHERE id = $value;
where $value is variable from 1st command
select * from your_table
where id = (select max(id) from your_table)
or
select t1.* from your_table t1
inner join
(
select max(id) as mid
from your_table
)
t2 on t1.id = t2.mid
Probably the simplest way is:
select *
from t
order by id
limit 1
Or use top 1 or where rownum = 1 or whatever is the right logic for your database.
Note: this only returns one row. If you have duplicate such rows, then comparison to the maximum will give you all of them.
Also, if you are using a database that supports window functions:
select *
from (select t.*, row_number() over (order by id desc) as seqnum
from t
) t
where seqnum = 1;
Table Essentially looks like:
Serial-ID, ID, Date, Data, Data, Data, etc.
There can be Multiple Rows for the Same ID. I'd like to create a view of this table to be used in Reports that only shows the most recent entry for each ID. It should show all of the columns.
Can someone help me with the SQL select? thanks.
There's about 5 different ways to do this, but here's one:
SELECT *
FROM yourTable AS T1
WHERE NOT EXISTS(
SELECT *
FROM yourTable AS T2
WHERE T2.ID = T1.ID AND T2.Date > T1.Date
)
And here's another:
SELECT T1.*
FROM yourTable AS T1
LEFT JOIN yourTable AS T2 ON
(
T2.ID = T1.ID
AND T2.Date > T1.Date
)
WHERE T2.ID IS NULL
One more:
WITH T AS (
SELECT *, ROW_NUMBER() OVER(PARTITION BY ID ORDER BY Date DESC) AS rn
FROM yourTable
)
SELECT * FROM T WHERE rn = 1
Ok, i'm getting carried away, here's the last one I'll post(for now):
WITH T AS (
SELECT ID, MAX(Date) AS latest_date
FROM yourTable
GROUP BY ID
)
SELECT yourTable.*
FROM yourTable
JOIN T ON T.ID = yourTable.ID AND T.latest_date = yourTable.Date
I would use DISTINCT ON
CREATE VIEW your_view AS
SELECT DISTINCT ON (id) *
FROM your_table a
ORDER BY id, date DESC;
This works because distinct on suppresses rows with duplicates of the expression in parentheses. DESC in order by means the one that normally sorts last will be first, and therefor be the one that shows in the result.
https://www.postgresql.org/docs/10/static/sql-select.html#SQL-DISTINCT
This seems like a good use for correlated subqueries:
CREATE VIEW your_view AS
SELECT *
FROM your_table a
WHERE date = (
SELECT MAX(date)
FROM your_table b
WHERE b.id = a.id
)
Your date column would need to uniquely identify each row (like a TIMESTAMP type).