I have a postgreSQL query which should be the actual stock of samples on our lab.
The initial samples are taken from a table (tblStudies), but then there are 2 tables to look for to decrease the amount of samples.
So I made a union query for those 2 tables, and then matched the uniun query with the tblStudies to calculate the actual stock.
But the union query only gives values when there is a decrease in samples.
So when the study still has it's initial samples, the value isn't returned.
I figured out I should use a JOIN operation, but then I have NULL values for my study with initial samples.
Here is how far I got, any help please?
SELECT
"tblStudies"."Studie_ID", "SamplesWeggezet", c."Stalen_gebruikt", "SamplesWeggezet" - c."Stalen_gebruikt" as "Stock"
FROM
"Stability"."tblStudies"
LEFT JOIN
(
SELECT b."Studie_ID",sum(b."Stalen_gebruikt") as "Stalen_gebruikt"
FROM (
SELECT "tblAnalyses"."Studie_ID", sum("tblAnalyses"."Aant_stalen_gebruikt") AS "Stalen_gebruikt"
FROM "Stability"."tblAnalyses"
GROUP BY "tblAnalyses"."Studie_ID"
UNION
SELECT "tblStalenUitKamer"."Studie_ID", sum("tblStalenUitKamer".aant_stalen) AS "stalen_gebruikt"
FROM "Stability"."tblStalenUitKamer"
GROUP BY "tblStalenUitKamer"."Studie_ID"
) b
GROUP BY b."Studie_ID"
) c ON "tblStudies"."Studie_ID" = c."Studie_ID"
Because you're doing a LEFT JOIN to the inline query "C" some values of c."stalen_gebruikt" can be null. And any number - null is going to yield null. To address this we can use coalesce
So change
"samplesweggezet" - c."stalen_gebruikt" AS "Stock
to
"samplesweggezet" - COALESCE(c."stalen_gebruikt",0) AS "Stock
Related
I need to calculate the difference of a column between two lines of a table. Is there any way I can do this directly in SQL? I'm using Microsoft SQL Server 2008.
I'm looking for something like this:
SELECT value - (previous.value) FROM table
Imagining that the "previous" variable reference the latest selected row. Of course with a select like that I will end up with n-1 rows selected in a table with n rows, that's not a probably, actually is exactly what I need.
Is that possible in some way?
Use the lag function:
SELECT value - lag(value) OVER (ORDER BY Id) FROM table
Sequences used for Ids can skip values, so Id-1 does not always work.
SQL has no built in notion of order, so you need to order by some column for this to be meaningful. Something like this:
select t1.value - t2.value from table t1, table t2
where t1.primaryKey = t2.primaryKey - 1
If you know how to order things but not how to get the previous value given the current one (EG, you want to order alphabetically) then I don't know of a way to do that in standard SQL, but most SQL implementations will have extensions to do it.
Here is a way for SQL server that works if you can order rows such that each one is distinct:
select rank() OVER (ORDER BY id) as 'Rank', value into temp1 from t
select t1.value - t2.value from temp1 t1, temp1 t2
where t1.Rank = t2.Rank - 1
drop table temp1
If you need to break ties, you can add as many columns as necessary to the ORDER BY.
WITH CTE AS (
SELECT
rownum = ROW_NUMBER() OVER (ORDER BY columns_to_order_by),
value
FROM table
)
SELECT
curr.value - prev.value
FROM CTE cur
INNER JOIN CTE prev on prev.rownum = cur.rownum - 1
Oracle, PostgreSQL, SQL Server and many more RDBMS engines have analytic functions called LAG and LEAD that do this very thing.
In SQL Server prior to 2012 you'd need to do the following:
SELECT value - (
SELECT TOP 1 value
FROM mytable m2
WHERE m2.col1 < m1.col1 OR (m2.col1 = m1.col1 AND m2.pk < m1.pk)
ORDER BY
col1, pk
)
FROM mytable m1
ORDER BY
col1, pk
, where COL1 is the column you are ordering by.
Having an index on (COL1, PK) will greatly improve this query.
LEFT JOIN the table to itself, with the join condition worked out so the row matched in the joined version of the table is one row previous, for your particular definition of "previous".
Update: At first I was thinking you would want to keep all rows, with NULLs for the condition where there was no previous row. Reading it again you just want that rows culled, so you should an inner join rather than a left join.
Update:
Newer versions of Sql Server also have the LAG and LEAD Windowing functions that can be used for this, too.
select t2.col from (
select col,MAX(ID) id from
(
select ROW_NUMBER() over(PARTITION by col order by col) id ,col from testtab t1) as t1
group by col) as t2
The selected answer will only work if there are no gaps in the sequence. However if you are using an autogenerated id, there are likely to be gaps in the sequence due to inserts that were rolled back.
This method should work if you have gaps
declare #temp (value int, primaryKey int, tempid int identity)
insert value, primarykey from mytable order by primarykey
select t1.value - t2.value from #temp t1
join #temp t2
on t1.tempid = t2.tempid - 1
Another way to refer to the previous row in an SQL query is to use a recursive common table expression (CTE):
CREATE TABLE t (counter INTEGER);
INSERT INTO t VALUES (1),(2),(3),(4),(5);
WITH cte(counter, previous, difference) AS (
-- Anchor query
SELECT MIN(counter), 0, MIN(counter)
FROM t
UNION ALL
-- Recursive query
SELECT t.counter, cte.counter, t.counter - cte.counter
FROM t JOIN cte ON cte.counter = t.counter - 1
)
SELECT counter, previous, difference
FROM cte
ORDER BY counter;
Result:
counter
previous
difference
1
0
1
2
1
1
3
2
1
4
3
1
5
4
1
The anchor query generates the first row of the common table expression cte where it sets cte.counter to column t.counter in the first row of table t, cte.previous to 0, and cte.difference to the first row of t.counter.
The recursive query joins each row of common table expression cte to the previous row of table t. In the recursive query, cte.counter refers to t.counter in each row of table t, cte.previous refers to cte.counter in the previous row of cte, and t.counter - cte.counter refers to the difference between these two columns.
Note that a recursive CTE is more flexible than the LAG and LEAD functions because a row can refer to any arbitrary result of a previous row. (A recursive function or process is one where the input of the process is the output of the previous iteration of that process, except the first input which is a constant.)
I tested this query at SQLite Online.
You can use the following funtion to get current row value and previous row value:
SELECT value,
min(value) over (order by id rows between 1 preceding and 1
preceding) as value_prev
FROM table
Then you can just select value - value_prev from that select and get your answer
I have 2 tables:
Query1: contains 3 columns, Due_Date, Received_Date, Diff
where Diff is the difference in the two dates in days
QueryHol with 2 columns, Date, Count
This has a list of dates and the count is set to 1 for everything. All these dates represent public holidays.
I want to be able to get the sum of QueryHol["Count"] if QueryHol["Date"] is between Query1["Due_Date"] and Query1["Received_Date"]
Result Wanted: a column joined onto Query1 to state how many public holidays fell into the date range so they can be subtracted from the Query1["Diff"] column to give a reflection of working days.
Because the 01-01-19 is a bank holiday i would want to minus that from the Diff to end up with results like below
Let me know if you require any more info.
Here's an option:
SELECT query1.due_date
, query1.received_date
, query1.diff
, queryhol.count
, COALESCE(query1.diff - queryhol.count, query1.diff) as DiffCount
FROM Query1
OUTER APPLY(
SELECT COUNT(*) AS count
FROM QueryHol
WHERE QueryHol.Date <= Query1.Received_Date
AND QueryHol.Date >= Query1.Due_Date
) AS queryhol
You may need to play around with the join condition - as it is assumes that the Received_Date is always later than the Due_Date which there is not enough data to know all of the use cases.
If I understand your problem, I think this is a possible solution:
select due_date,
receive_date,
diff,
(select sum(table2.count)
from table2
where table2.due_date between table1.due_date and table1.due_date) sum_holi,
table1.diff - (select sum(table2.count)
from table2
where table2.date between table1.due_date and table2.due_date) diff_holi
from table1
where [...] --here your conditions over table1.
I got an error when I tried to solve this problem. First I need to count all values of 2 tables then I need in where condition get all max values.
My code:
Select *
FROM (
select Operator.OperatoriausPavadinimas,
(
select count(*)
from Plan
where Plan.operatoriausID= Operator.operatoriausID
) as NumberOFPlans
from Operator
)a
where a.NumberOFPlans= Max(a.NumberOFPlans)
I get this error
Msg 147, Level 15, State 1, Line 19
An aggregate may not appear in the WHERE clause unless it is in a subquery contained in a HAVING clause or a select list, and the column being aggregated is an outer reference.
I don't know how to solve this.
I need get this http://prntscr.com/p700w9
Update 1
Plan table contains of http://prntscr.com/p7055l values and
Operator table contains of http://prntscr.com/p705k0 values.
Are you looking for... an aggregate query that joins both tables and returns the record that has the maximum count?
I suspect that this might phrase as follows:
SELECT TOP(1) o.OperatoriausPavadinimas, COUNT(*)
FROM Operatorius o
INNER JOIN Planas p ON p.operatoriausID = o.operatoriausID
GROUP BY o.OperatoriausPavadinimas
ORDER BY COUNT(*) DESC
If you want to allow ties, you can use TOP(1) WITH TIES.
You can use top with ties. Your query is a bit hard to follow, but I think you want:
select top (1) with ties o.OperatoriausPavadinimas, count(*)
from plan p join
operator o
on p.operatoriausID = o.operatoriausID
group by o.OperatoriausPavadinimas
order by count(*) desc;
I'm still fairly new to SQL. This is a stripped down version of the query I'm trying to run. This query is suppose to find those customers with more than 3 cases and display either the top 1 case or all cases but still show the overall count of cases per customer in each row in addition to all the case numbers.
The TOP 1 subquery approach didn't work but is there another way to get the results I need? Hope that makes sense.
Here's the code:
SELECT t1.StoreID, t1.CustomerID, t2.LastName, t2.FirstName
,COUNT(t1.CaseNo) AS CasesCount
,(SELECT TOP 1 t1.CaseNo)
FROM MainDatabase t1
INNER JOIN CustomerDatabase t2
ON t1.StoreID = t2.StoreID
WHERE t1.SubmittedDate >= '01/01/2017' AND t1.SubmittedDate <= '05/31/2017'
GROUP BY t1.StoreID, t1.CustomerID, t2.LastName, t2.FirstName
HAVING COUNT (t1.CaseNo) >= 3
ORDER BY t1.StoreID, t1.PatronID
I would like it to look something like this, either one row with just the most recent case and detail or several rows showing all details of each case in addition to the store id, customer id, last name, first name, and case count.
Data Example
For these I usually like to make a temp table of aggregates:
DROP TABLE IF EXISTS #tmp;
CREATE TABLE #tmp (
CustomerlD int NOT NULL DEFAULT 0,
case_count int NOT NULL DEFAULT 0,
case_max int NOT NULL DEFAULT 0,
);
INSERT INTO #tmp
(CustomerlD, case_count, case_max)
SELECT CustomerlD, COUNT(tl.CaseNo), MAX(tl.CaseNo)
FROM MainDatabase
GROUP BY CustomerlD;
Then you can join this "tmp" table back to any other table you want to display the number of cases on, or the max case number on. And you can limit it to customers that have more than 3 cases with WHERE case_count > 3
Suppose I have a table called Transaction and another table called Price. Price holds the prices for given funds at different dates. Each fund will have prices added at various dates, but they won't have prices at all possible dates. So for fund XYZ I may have prices for the 1 May, 7 May and 13 May and fund ABC may have prices at 3 May, 9 May and 11 May.
So now I'm looking at the price that was prevailing for a fund at the date of a transaction. The transaction was for fund XYZ on 10 May. What I want, is the latest known price on that day, which will be the price for 7 May.
Here's the code:
select d.TransactionID, d.FundCode, d.TransactionDate, v.OfferPrice
from Transaction d
inner join Price v
on v.FundCode = d.FundCode
and v.PriceDate = (
select max(PriceDate)
from Price
where FundCode = v.FundCode
/* */ and PriceDate < d.TransactionDate
)
It works, but it is very slow (several minutes in real world use). If I remove the line with the leading comment, the query is very quick (2 seconds or so) but it then uses the latest price per fund, which is wrong.
The bad part is that the price table is minuscule compared to some of the other tables we use, and it isn't clear to me why it is so slow. I suspect the offending line forces SQL Server to process a Cartesian product, but I don't know how to avoid it.
I keep hoping to find a more efficient way to do this, but it has so far escaped me. Any ideas?
You don't specify the version of SQL Server you're using, but if you are using a version with support for ranking functions and CTE queries I think you'll find this quite a bit more performant than using a correlated subquery within your join statement.
It should be very similar in performance to Andriy's queries. Depending on the exact index topography of your tables, one approach might be slightly faster than another.
I tend to like CTE-based approaches because the resulting code is quite a bit more readable (in my opinion). Hope this helps!
;WITH set_gen (TransactionID, OfferPrice, Match_val)
AS
(
SELECT d.TransactionID, v.OfferPrice, ROW_NUMBER() OVER(PARTITION BY d.TransactionID ORDER BY v.PriceDate ASC) AS Match_val
FROM Transaction d
INNER JOIN Price v
ON v.FundCode = d.FundCode
WHERE v.PriceDate <= d.TransactionDate
)
SELECT sg.TransactionID, d.FundCode, d.TransactionDate, sg.OfferPrice
FROM Transaction d
INNER JOIN set_gen sg ON d.TransactionID = sg.TransactionID
WHERE sg.Match_val = 1
There's a method for finding rows with maximum or minimum values, which involves LEFT JOIN to self, rather than more intuitive, but probably more costly as well, INNER JOIN to a self-derived aggregated list.
Basically, the method uses this pattern:
SELECT t.*
FROM t
LEFT JOIN t AS t2 ON t.key = t2.key
AND t2.Value > t.Value /* ">" is when getting maximums; "<" is for minimums */
WHERE t2.key IS NULL
or its NOT EXISTS counterpart:
SELECT *
FROM t
WHERE NOT EXISTS (
SELECT *
FROM t AS t2
WHERE t.key = t2.key
AND t2.Value > t.Value /* same as above applies to ">" here as well */
)
So, the result is all the rows for which there doesn't exist a row with the same key and the value greater than the given.
When there's just one table, application of the above method is pretty straightforward. However, it may not be that obvious how to apply it when there's another table, especially when, like in your case, the other table makes the actual query more complex not merely by its being there, but also by providing us with an additional filtering for the values we are looking for, namely with the upper limits for the dates.
So, here's what the resulting query might look like when applying the LEFT JOIN version of the method:
SELECT
d.TransactionID,
d.FundCode,
d.TransactionDate,
v.OfferPrice
FROM Transaction d
INNER JOIN Price v ON v.FundCode = d.FundCode
LEFT JOIN Price v2 ON v2.FundCode = v.FundCode /* this and */
AND v2.PriceDate > v.PriceDate /* this are where we are applying
the above method; */
AND v2.PriceDate < d.TransactionDate /* and this is where we are limiting
the maximum value */
WHERE v2.FundCode IS NULL
And here's a similar solution with NOT EXISTS:
SELECT
d.TransactionID,
d.FundCode,
d.TransactionDate,
v.OfferPrice
FROM Transaction d
INNER JOIN Price v ON v.FundCode = d.FundCode
WHERE NOT EXISTS (
SELECT *
FROM Price v2
WHERE v2.FundCode = v.FundCode /* this and */
AND v2.PriceDate > v.PriceDate /* this are where we are applying
the above method; */
AND v2.PriceDate < d.TransactionDate /* and this is where we are limiting
the maximum value */
)
Are both pricedate and transactiondate indexed? If not you are doing table scans which is likely the cause of the performance bottleneck.