After many attempts I have failed at this and hoping someone can help. The query returns every entry a user makes when items are made in the factory against and order number. For example
Order Number Entry type Quantity
3000 1 1000
3000 1 500
3000 2 300
3000 2 100
4000 2 1000
5000 1 1000
What I want to the query do is to return filter the results like this
If the order number has an entry type 1 and 2 return the row which is type 1 only
otherwise just return row whatever the type is for that order number.
So the above would end up:
Order Number Entry type Quantity
3000 1 1000
3000 1 500
4000 2 1000
5000 1 1000
Currently my query (DB2, in very basic terms looks like this ) and was correct until a change request came through!
Select * from bookings where type=1 or type=2
thanks!
select * from bookings
left outer join (
select order_number,
max(case when type=1 then 1 else 0 end) +
max(case when type=2 then 1 else 0 end) as type_1_and_2
from bookings
group by order_number
) has_1_and_2 on
type_1_and_2 = 2
has_1_and_2.order_number = bookings.order_number
where
bookings.type = 1 or
has_1_and_2.order_number is null
Find all the orders that have both type 1 and type 2, and then join it.
If the row matched the join, only return it if it is type 1
If the row did not match the join (has_type_2.order_number is null) return it no matter what the type is.
A "common table expression" [CTE] can often simplify your logic. You can think of it as a way to break a complex problem into conceptual steps. In the example below, you can think of g as the name of the result set of the CTE, which will then be joined to
WITH g as
( SELECT order_number, min(type) as low_type
FROM bookings
GROUP BY order_number
)
SELECT b.*
FROM g
JOIN bookings b ON g.order_number = b.order_number
AND g.low_type = b.type
The JOIN ON conditions will work so that if both types are present then low_type will be 1, and only that type of record will be chosen. If there is only one type it will be identical to low_type.
This should work fine as long as 1 and 2 are the only types allowed in the bookings table. If not then you can simply add a WHERE clause in the CTE and in the outer SELECT.
Related
I have an MS Access database with the two tables, Asset and Transaction. The schema looks like this:
Table ASSET
Key Date1 AType FieldB FieldC ...
A 2023.01.01 T1
B 2022.01.01 T1
C 2023.01.01 T2
.
.
TABLE TRANSACTION
Date2 Key TType1 TType2 TType3 FieldOfInterest ...
2022.05.31 A 1 1 1 10
2022.08.31 A 1 1 1 40
2022.08.31 A 1 2 1 41
2022.09.31 A 1 1 1 30
2022.07.31 A 1 1 1 30
2022.06.31 A 1 1 1 20
2022.10.31 A 1 1 1 45
2022.12.31 A 2 1 1 50
2022.11.31 A 1 2 1 47
2022.05.23 B 2 1 1 30
2022.05.01 B 1 1 1 10
2022.05.12 B 1 2 1 20
.
.
.
The ASSET table has a PK (Key).
The TRANSACTION table has a composite key that is (Key, Date2, Type1, Type2, Type3).
Given the above tables let's see an example:
Input1 = 2022.04.01
Input2 = 2022.08.31
Desired result:
Key FieldOfInterest
A 41
because if the Transactions in scope was to be ordered by Date2, TType1, TType2, TType3 all ascending then the record having FieldOfInterest = 41 would be the last one.
Note that Asset B is not in scope due to Asset.Date1 < Input1, neither is Asset C because AType != T1. Ultimately I am curious about the SUM(FieldOfInterest) of all the last transactions belonging to an Asset that is in scope determined by the input variables.
The following query has so far provided the right results but after upgrading to a newer MS Access version, the LAST() operation is no longer reliably returning the row which is the latest addition to the Transaction table.
I have several input values but the most important ones are two dates, lets call them InputDate1 and
InputDate2.
This is how it worked so far:
SELECT Asset.AType, Last(FieldOfInterest) AS CurrentValue ,Asset.Key
FROM Transaction
INNER JOIN Asset ON Transaction.Key = Asset.Key
WHERE Transaction.Date2 <= InputDate2 And Asset.Date1 >= InputDate1
GROUP BY Asset.Key, Asset.AType
HAVING Asset.AType='T1'
It is known that the grouped records are not guaranteed to be in any order. Obviously it is a mistake to rely on the order of the records of the group by operation will always keep the original table order but lets just ignore this for now.
I have been struggling to come up with the right way to do the following:
join the Asset and Transaction tables on Asset.Key = Transaction.Key
filter by Asset.Date1 >= InputDate1 AND Transaction.Date2 <= InputDate2
then I need to select one record for all Transaction.Key where Date2 and TType1 and TType2 and TType3 has the highest value. (this represents the actual last record for given Key)
As far as I know there is no way to order records within a group by clause which is unfortunate.
I have tried Ranking, but the Transactions table is large (800k rows) and the performance was very slow, I need something faster than this. The following are an example of three saved queries that I wrote and chained together but the performance is very disappointing probably due to the ranking step.
-- Saved query step_1
SELECT Asset.*, Transaction.*
FROM Transaction
INNER JOIN Asset ON Transaction.Key = Asset.Key
WHERE Transaction.Date2 <= 44926
AND Asset.Date1 >= 44562
AND Asset.aType = 'T1'
-- Saved query step_2
SELECT tr.FieldOfInterest, (SELECT Count(*) FROM
(SELECT tr2.Transaction.Key, tr2.Date2, tr2.Transaction.tType1, tr2.tType2, tr2.tType3 FROM step_1 AS tr2) AS tr1
WHERE (tr1.Date2 > tr.Date2 OR
(tr1.Date2 = tr.Date2 AND tr1.tType1 > tr.Transaction.tType1) OR
(tr1.Date2 = tr.Date2 AND tr1.tType1 = tr.Transaction.tType1 AND tr1.tType2 > tr.tType2) OR
(tr1.Date2 = tr.Date2 AND tr1.tType1 = tr.Transaction.tType1 AND tr1.tType2 = tr.tType2 AND tr1.tType3 > tr.tType3))
AND tr1.Key = tr.Transaction.Key)+1 AS Rank
FROM step_1 AS tr
-- Saved query step_3
SELECT SUM(FieldOfInterest) FROM step_2
WHERE Rank = 1
I hope I am being clear enough so that I can get some useful recommendations. I've been stuck with this for weeks now and really don't know what to do about it. I am open for any suggestions.
Reading the following specification
then I need to select one record for all Transaction.Key where Date2 and TType1 and TType2 and TType3 has the highest value. (this represents the actual last record for given Key)
Consider a simple aggregation for step 2 to retrieve the max values then in step 3 join all fields to first query.
Step 1 (rewritten to avoid name collision and too many columns)
SELECT a.[Key] AS Asset_Key, a.Date1, a.AType,
t.[Key] AS Transaction_Key, t.Date2,
t.TType1, t.TType2, t.TType3, t.FieldOfInterest
FROM Transaction t
INNER JOIN Asset a ON a.[Key] = a.[Key]
WHERE t.Date2 <= 44926
AND a.Date1 >= 44562
AND a.AType = 'T1'
Step 2
SELECT Transaction_Key,
MAX(Date2) AS Max_Date2,
MAX(TType1) AS TType1,
MAX(TType2) AS TType2,
MAX(TType3) AS TType3
FROM step_1
GROUP Transaction_Key
Step 3
SELECT s1.*
FROM step_1 s1
INNER JOIN step_2 s2
ON s1.Transaction_Key = s2.Transaction_Key
AND s1.Date2 = s2.Max_Date2
AND s1.TType1 = s2.Max_TType1
AND s1.TType2 = s2.Max_TType2
AND s1.TType3 = s2.Max_TType3
I'm not even sure how to ask this. So here goes. I have two tables I am joining, and am needing to sum one column of data, easy enough, but the data that needs to be summed is dependent on a certain character associated with the same job number from a different table.
Table1
JobNumber CostType Amount
1 A 10
1 B 20
1 C 50
1 C 50
3 C 75
Table 2
JobNumber Status Value
1 A 100
2 I 50
3 A 75
Okay, so some of the jobs will have multiple lines for CostType 'C'. I'm trying to display all JobNumbers with the total of any amounts for CostType C, BUT only for jobs that have the Status of 'A'. Here's my query so far:
SELECT Table1.JobNumber
,Table1.Amount
,Table2.Value
FROM DB.Table1, DB.Table2
WHERE Table1.JobNumber = Table2.JobNumber and Table1.CostType = 'C' and Table2.Status = 'A'
GROUP BY Table1.JobNumber, Table1.Amount, Table2.Value
ORDER BY Table1.JobNumber ASC
It's giving me the list of job numbers, their amounts, and the contract value, and only for CostType 'C' and with the Status of 'A'. But each separate CostType 'C' amount has its own row. Is there a way to combine them and display the total Amount along with the Value for each JobNumber, like this?
JobNumber CostTypeCTotal Value
1 100 100
3 75 75
Hmmm . . . Try aggregating table1 before joining the tables:
SELECT t2.JobNumber, t1.c_Amount, t2.Value
FROM DB.Table2 t2
(SELECT JobNumber,
SUM(CASE WHEN CostType = 'C' THEN amount END) as c_amount
FROM DB.Table1 t1
GROUP BY JobNumber
HAVING SUM(CASE WHEN CostType = 'A' THEN 1 ELSE 0 END) > 0
) t1 JOIN
ON t1.JobNumber = t2.JobNumber;
Note: Learn to use proper, explicit, standard, readable JOIN syntax. Never use commas in the FROM clause. Such use of , is archaic syntax that has been out of date since the 1990s.
I'm looking to filter out rows in the database (PostgreSQL) if one of the values in the status column occurs. The idea is to sum the amount column if the unique reference only has a status equals to 1. The query should not SELECT the reference at all if it has also a status of 2 or any other status for that matter. status refers to the state of the transaction.
Current data table:
reference | amount | status
1 100 1
2 120 1
2 -120 2
3 200 1
3 -200 2
4 450 1
Result:
amount | status
550 1
I've simplified the data example but I think it gives a good idea of what I'm looking for.
I'm unsuccessful in selecting only references that only have status 1.
I've tried sub-queries, using the HAVING clause and other methods without success.
Thanks
Here's a way using not exists to sum all rows where the status is 1 and other rows with the same reference and a non 1 status do not exist.
select sum(amount) from mytable t1
where status = 1
and not exists (
select 1 from mytable t2
where t2.reference = t1.reference
and t2.status <> 1
)
SELECT SUM(amount)
FROM table
WHERE reference NOT IN (
SELECT reference
FROM table
WHERE status<>1
)
The subquery SELECTs all references that must be excluded, then the main query sums everything except them
select sum (amount) as amount
from (
select sum(amount) as amount
from t
group by reference
having not bool_or(status <> 1)
) s;
amount
--------
550
You could use windowed functions to count occurences of status different than 1 per each group:
SELECT SUM(amount) AS amount
FROM (SELECT *,COUNT(*) FILTER(WHERE status<>1) OVER(PARTITION BY reference) cnt
FROM tc) AS sub
WHERE cnt = 0;
Rextester Demo
I want to get all the possible type from a table and then count the rows under a group who has this type.
To better illustrate consider the following table.
Object (o)
id name group_id type
-----------------------------------------------------------
1 Computer 100 A
2 Monitor 100 A
3 Chair 100 B
4 Table 100 B
5 Telephone 100 C
6 Notebook 200 D
7 Pen 200 D
8 Wire 100 E
What I want to get is the following result:
group_id type total
-------------------------------
100 A 2
100 B 2
100 C 1
100 D 0
100 E 1
The group_id doesn't have to be included in the result, I just wanted to let you see here that I'm using a WHERE clause in my query. Basically I only want the results for group | 100 but I want the counts for all type.
Using my query below
SELECT o.group_id, o.type, COUNT(*) AS total
FROM object o
WHERE o.group_id = 100
GROUP BY o.type
I only get the following result:
group_id type total
-------------------------------
100 A 2
100 B 2
100 C 1
100 E 1
You will notice that I am missing the row for type | D. I also want to include that.
You can use the following query:
SELECT 100 AS group_id,
o.type,
COUNT(CASE WHEN o.group_id = 100 THEN 1 END) AS total
FROM object o
GROUP BY o.type
This query groups by type and uses conditional aggregation so as to count the rows under each group who have type = 100.
The problem is that Type D is not returned in the query for that ID, so it is not included in the groupings. To do this, we need to get the list of ALL Types in the table, then do the counts for your ID in the table. Something like this:
SELECT o_list.type, COUNT(o.id) AS total
FROM object o
RIGHT OUTER JOIN ( SELECT DISTINCT type from object ) o_list on o_list.type = o.type
WHERE o.group_id = 100
GROUP BY o_list.type
Giorgos's version is, arguably, cleaner to read and will always run in one full scan of the table. Mine is more complex, but if there are indexes on group_id and type, will run on index scans and so may be significantly faster on a large data set.
And you get to see that there are always options on how to solve a problem. :)
Since Type isn't in group 100 I first get a distinct set of types, then join back to objects since you want 100 for type D, I always show 100 when the type doesn't exist.
SELECT coalesce(O.Group_ID,100) as Group_ID, T.Type, count(O.Group_ID) as Total
FROM (Select Distinct Type from object) T
LEFT JOIN Object O
on T.Type = O.Type
GROUP BY coalesce(O.Group_ID,100), T.Type
I want to identify the users who visited section a and then subsequently visited b. Given the following data structure. The table contains 300,000 rows and updates daily with approx. 8,000 rows:
**USERID** **VISITID** **SECTION** Desired Solution--> **Conversion**
1 1 a 0
1 2 a 0
2 1 b 0
2 1 b 0
2 1 b 0
1 3 b 1
Ideally I want a new column that flags the visit to section b. For example on the third visit User 1 visited section b for the first time. I was attempting to do this using a CASE WHEN statement but after many failed attempts I am not sure it is even possible with CASE WHEN and feel that I should take a different approach, I am just not sure what that approach should be. I do also have a date column at my disposal.
Any suggestions on a new way to approach the problem would be appreciated. Thanks!
Correlated sub-queries should be avoided at all cost when working with Redshift. Keep in mind there are no indexes for Redshift so you'd have to rescan and restitch the column data back together for each value in the parent resulting in an O(n^2) operation (in this particular case going from 300 thousand values scanned to 90 billion).
The best approach when you are looking to span a series of rows is to use an analytic function. There are a couple of options depending on how your data is structured but in the simplest case, you could use something like
select case
when section != lag(section) over (partition by userid order by visitid)
then 1
else 0
end
from ...
This assumes that your data for userid 2 increments the visitid as below. If not, you could also order by your timestamp column
**USERID** **VISITID** **SECTION** Desired Solution--> **Conversion**
1 1 a 0
1 2 a 0
2 1 b 0
2 *2* b 0
2 *3* b 0
1 3 b 1
select t.*, case when v.ts is null then 0 else 1 end as conversion
from tbl t
left join (select *
from tbl x
where section = 'b'
and exists (select 1
from tbl y
where y.userid = x.userid
and y.section = 'a'
and y.ts < x.ts)) v
on t.userid = v.userid
and t.visitid = v.visitid
and t.section = v.section
Fiddle:
http://sqlfiddle.com/#!15/5b954/5/0
I added sample timestamp data as that field is necessary to determine whether a comes before b or after b.
To incorporate analytic functions you could use:
(I've also made it so that only the first occurrence of B (after an A) will get flagged with the 1)
select t.*,
case
when v.first_b_after_a is not null
then 1
else 0
end as conversion
from tbl t
left join (select userid, min(ts) as first_b_after_a
from (select t.*,
sum( case when t.section = 'a' then 1 end)
over( partition by userid
order by ts ) as a_sum
from tbl t) x
where section = 'b'
and a_sum is not null
group by userid) v
on t.userid = v.userid
and t.ts = v.first_b_after_a
Fiddle: http://sqlfiddle.com/#!1/fa88f/2/0