I have two tables.
T1
id,date,item,channel
T2
id,date,item,channel
In T2 the id and date columns are NULL. I want to randomly assign an id and date from T1 to each row in T2. Also, T2 is much smaller than T1.
Any ideas how to do this? I'm on Teradata 13.
I was originally thinking something like this:
sel count(*) from t2 ;
--507
select *
from (sel a.*, RANDOM(1,507) as r1 from t1) a
inner join (sel b.*, RANDOM(1,507) as r1 from t2) b
on a.r1 = b.r1
The problem is I'll need to automatically assign the count of t2 as the upper bound of random.
Assign a ROW_NUMBER based on a RANDOM sort and join on that:
select *
from
(
select dt.*, row_number() over (order by t1.r) as rn
from
(
select t1.*, RANDOM(1,1000000) as r from t1
) as dt
) as a
join
(
select dt.*, row_number() over (order by t1.r) as rn
from
(
select t2.*, RANDOM(1,1000000) as r from t2
) as dt
) as b
on a.rn = b.rn
Related
Currently trying to figure out how to implement a SQL LEFT OUTER JOIN while using the SQL WITH AS clause. My code breaks down into 3 SELECT statements while using the same table, then using LEFT OUTER JOIN to merge another table on the id.
I need 3 SELECT statements before joining because I need a SELECT statement to grab the needed columns, ROW RANK the time, and set WHERE clause for the ROW RANK.
SELECT *
(
WITH employee AS
(
SELECT id, name, department, code, time, reporttime, scheduled_time
FROM table1 AS a
WHERE department = "END"
),
employe_v2 as
(
SELECT address
,ROW_NUMBER() OVER (PARTITION BY id ORDER BY time desc, reporttime desc, scheduled_time desc) AS row_rank
FROM table1 AS b
)
SELECT *
FROM employee, employee_v2
WHERE row_rank = 1
) t1
LEFT OUTER JOIN
(
SELECT b.id, b.new_code, b.date
FROM table2 AS b
WHERE b.newcode != "A"
) t2
ON t1.id = t2.id
Group BY t1.id, t1.name, t1.department, t1.code, t1.time, t1.reporttime,
t1.scheduled_time, t1.row_rank, t2.id, t2.new_code, t2.date
How I could fix my code?
not sure if group by is needed, i see no aggregation whatsover
but if it's something you need , you can add at the end of final select and ofcourse you have to take care of columns/aggregation in select
nevertheless you can simplify your query as below :
with employee as (
select * from (
select id, name, department, code, time, reporttime, scheduled_time, address
,row_number() over (partition by id order by time desc, reporttime desc, scheduled_time desc) AS row_rank
from table1
) t where row_rank =1
)
select t1.*, b.id, b.new_code, b.date
from employee t1
left join table2 as t2
on t1.id = t2.id
where t2.newcode != "A"
I have two tables that I am trying to JOIN
table1
----------------------------
Id Name Num
123X Apple 17
table2
-------------------------------------------------
id EndDt SomeVal
123X 10/1/2021 xxx
123X 3/1/2022 yyy
I am attempting to Select from table1 a and LEFT JOIN table2 b on a.id = b.id - however, I want to only select on the id in table2 where MAX(EndDt)
Select a.*, b.SomeVal
from table1 a
LEFT OUTER JOIN table2 b on a.id=b.id // and b.MAX(EndDt)
Is something like that doable?
There are a few ways you can do this. I make some assumptions on your data though.
Use a LEFT JOIN with a subquery:
SELECT T1.*,
sq.SomeVal
FROM dbo.Table1 T1
LEFT JOIN (SELECT ROW_NUMBER() OVER (PARTITION BY t2.Id ORDER BY t2.EndDt DESC) AS RN,
t2.Id,
t2.SomeVal
FROM dbo.Table2 T2) sq ON T1.Id = T2.Id
AND T2.RN = 1;
Use APPLY and TOP:
SELECT T1.*,
sq.SomeVal
FROM dbo.Table1 T1
OUTER APPLY (SELECT TOP (1)
t2.Id,
t2.SomeVal
FROM dbo.Table2 T2
WHERE T2.Id = T1.Id
ORDER BY T2.EndDt DESC) sq;
Use a CTE and get the "top 1" row per group:
WITH CTE AS(
SELECT T1.*,
T2.SomeVal,
ROW_NUMBER() OVER (PARTITION BY T1.ID ORDER BY T2.MaxDt DESC) AS RN
FROM dbo.Table1 T1
LEFT JOIN dbo.Table2 T2 ON T1.Id = T2.Id)
SELECT *
FROM CT
WHERE RN = 1;
Use TOP (1) WITH TIES:
SELECT TOP (1) WITH TIES
T1.*,
T2.SomeVal
FROM dbo.Table1 T1
LEFT JOIN dbo.Table2 T2 ON T1.Id = T2.Id
ORDER BY ROW_NUMBER() OVER (PARTITION BY T1.ID ORDER BY T2.MaxDt DESC) ASC;
Note that options 3 and 4 won't work as expected if ID is not unique in the table Table1 (hence my assumptions about your data).
I would recommend using the windowed ROW_NUMBER function to take the max table2 first, and then join into that subquery.
;WITH cte AS (
SELECT *, [Row] = ROW_NUMBER() OVER (PARTITION BY b.Id ORDER BY b.EndDt DESC)
FROM table2 b
)
SELECT a.*, cte.SomeVal
FROM table1 a
LEFT JOIN cte ON a.id = cte.id AND cte.[Row] = 1
For a single value, use a correlated sub-query:
SELECT
a.id,
a.name,
a.num,
(
SELECT TOP 1 SomeValue
FROM table2 As b
WHERE b.id = a.id
ORDER BY b.EndDt DESC
) As SomeVal
FROM
table1 a
I am trying to select multiple values from two tables but i want to group by single value. I have tried using max(value) in select but max is returning the greatest one and not the exact one.
Here are my tables
The result i need is something like this
Result : HeadQuarterId - A, PropertyName - Name1, Amount - 102
HeadQuarterId - B, PropertyName - Name5, Amount - 30
Here is my query
SELECT Headquarterid,Max(PropertyName),sum(Amount)
FROM Table1 A LEFT OUTER JOIN Table2 B
ON A.Propetyid = B.PropertyId
GROUP BY Headquarterid
Here i have used Left Outer Join so that i will get all the data from left table even it is not available in right table.
Also i cannot use A.HeadquarterID = A.PropertyId in where condition since i have other dependency in that table. Please suggest someother way to achieve this result.
I think I understand. You want the headquarters with the maximum value, which happens to be A. If so:
select t1.*, sum(t2.amount) over () as total
from t1 left join
t2
on t2.PropertyId = t1.PropertyId
order by t2.amount desc
fetch first 1 row only;
Note: Not all databases support fetch first. It might be spelled limit or use select top (1) for instance.
I would recommend to get the headquartename per ID in a cte / subquery, then join it again to T1 and left join T1 to T2 in a second cte / subquery. This way you can calculate your sums basing on a single group:
WITH cte AS(
SELECT ROW_NUMBER() OVER (PARTITION BY t1.ID ORDER BY CASE WHEN t1.ID = t1.PROPERTYID THEN 0 ELSE 1 END) rn, t1.ID, t1.Name
FROM t1
),
cte2 AS(
SELECT c.name cName, t1.*, t2.Value
FROM t1
INNER JOIN cte c ON c.ID = t1.ID AND c.rn = 1
LEFT JOIN t2 ON t1.Propertyid = t2.propertyid
)
SELECT c2.id, c2.cname, sum(c2.value) value
FROM cte2 c2
GROUP BY c2.id, c2.cname
See SQLFiddle for details: http://sqlfiddle.com/#!18/8bf66/13/2
Of course you can build the first cte without the row_number only by using the WHERE ID = PROPERTYID - matter of taste I'd say...
As per your sample data you want window function :
select distinct t1.HeadQuarterId,
max(t1.PropertyName) over (partition by t1.HeadQuarterId) as PropertyName,
sum(t2.amount) over (partition by t1.HeadQuarterId) as amount
from t1 left join
t2
on t2.PropertyId = t1.PropertyId;
This provided the result i expected.
SELECT HQTRS1 AS headId,Max(LLORD1) AS headName, sum(Amount) AS amount
FROM
(SELECT DISTINCT HeadQuarterId AS HQTRS1, PropertyName AS LLORD1 FROM Table_1 WHERE HeadQuarterId = PropertyId) AS temp
INNER JOIN Table_1 AS A ON A.HeadQuarterId = temp.HQTRS1
LEFT OUTER JOIN Table_2 B
ON B.PropertyId = A.PropertyId
GROUP BY HQTRS1
this is my table layout simplified:
table1: pID (pkey), data
table2: rowID (pkey), pID (fkey), data, date
I want to select some rows from table1 joining one row from table2 per pID for the most recent date for that pID.
I currently do this with the following query:
SELECT * FROM table1 as a
LEFT JOIN table2 AS b ON b.rowID = (SELECT TOP(1) rowID FROM table2 WHERE pID = a.pID ORDER BY date DESC)
This way of working is slow, probabaly because it has to do a subquery on each row of table 1. Is there a way to improve performance on this or do it another way?
You can try something on these lines, use the subquery to get the latest based on the date field (grouping by the pID), then join that with the first table, this way the subquery would not have not have to be executed for each row of Table1 and will result in better performance:
Select *
FROM Table1 a
INNER JOIN
(
SELECT pID, Max(Date) FROM Table2
GROUP BY pID
) b
ON a.pID = b.pID
I have provided the sample SQL for one column using the group by, in case you need additional columns, add them to the GROUP BY clause. Hope this helps.
use the below code, and note that i added the order by Date desc to get the most resent data
select *
from table1 a
inner join table2 b on a.pID=b.pID
where b.rowID in(select top(1) from table2 t where t.pID=a.pID order by Date desc)
I am using the code below in a similar scenaro (I transcripted it to your example)
SELECT b.*
FROM table1 AS a
left outer join (
SELECT a.*
FROM table2 a
inner join (
SELECT a.pID, max(date) as date
FROM table2
WHERE date <= <max_date>
group by pID
) b ON a.pID = b.pID AND a.date = b.date
) b ON a.pID = b.pID
) b on a.pID = b.pID
The only problem with this aproach is that you have to make sure the date's don't reapet for the pID's
You can do this with the row_number() function and a subquery:
SELECT t1.*
FROM table1 t1 LEFT JOIN
(select t2.*, row_number() over (partition by pId order by rowId desc) as seqnum
from table2 t2
) t2
on t1.pId = t2.pId and t2.seqnum = 1;
Use the ROW_NUMBER() function to get a column saying which id of each row in table 2 is the first (As partitioned by the pID, and ordered by the rowDate descending)
Example:
WITH cte AS
(
SELECT
rowID AS t2RowId,
ROW_NUMBER OVER (PARTITION BY pID ORDER BY rowDate DESC) AS rowNum
FROM table2 t2
) -- gets the t2RowIds + a column which says which is the latest for each pID
SELECT t1.*, t2.*
FROM table1 t1
LEFT JOIN
(
table2 t2
JOIN cte ON t2.rowID = cte.t2RowId AND cte.rowNum = 1
) ON t1.pID = t2.pID
This is guaranteed to only return 1 item from table2 per pID, even if multiple items have the same date. You should of course ensure that the date column is indexed in table 2 for quick performance (ideally an index that also covers the PrimaryID of table2)
i need an sql query which should return the master table entry and its child table entry (the latest one entry only). I used inner join for this. But i its not working fine.
Can anyone give a give me a proper query for this
Thanks in advance
In SQLServer2005+ use option with OUTER APPLY operator
SELECT *
FROM master t1 OUTER APPLY (
SELECT TOP 1 t2.Col1, t2.Col2 ...
FROM child t2
WHERE t1.Id = t2.Id
ORDER BY t2.CreatedDate DESC
) o
OR option with CTE and ROW_NUMBER() ranking function
;WITH cte AS
(
SELECT *,
ROW_NUMBER() OVER(PARTITION BY t1.Id ORDER BY t2.CreatedDate DESC) AS rn
FROM master t1 JOIN child t2 ON t1.Id = t2.Id
)
SELECT *
FROM cte
WHERE rn = 1
Try this,
SELECT ID, DATE
(
SELECT M.ID, C.DATE, ROW_NUMBER() OVER(PARTITION BY M.ID ORDER BY C.DATE DESC) RN
FROM MASTER M
JOIN CHILD C
ON C.ID = M.ID
) A
WHERE RN = 1