I want to join two select statements into one. How do look like query to combine two results?
SELECT Name FROM students WHERE No = 4
SELECT TOP 1 pchar FROM pcharacter ORDER BY NEWID();
I tried this;
SELECT TOP 1 students.Name, pcharacter.pchar
FROM students, pcharacter
WHERE No = 4
ORDER BY NEWID();
Is this the proper way or not? I get desired result.
It appears you're attempting to associate a random row from the pcharacter table with each row from the students table WHERE No=4. As such CROSS APPLY seems appropriate
SELECT s.[Name], pc.pchar
FROM students s
cross apply (select top 1 pchar
from pcharacter
order by newid()) pc
WHERE s.[No]=4;
Query results are tables again, so you can join them just like you join stored tables. For instance:
SELECT *
FROM
(SELECT Name FROM students WHERE No = 4) query1
CROSS JOIN
(SELECT TOP 1 pchar FROM pcharacter ORDER BY NEWID()) query2
;
As to your own query: The query is quite okay. You select one student and join it with all characters and then pick one of the resulting rows randomly. It would be better of course to pick one random character first and only then join with the student. Just as you have said: Join the two queries. And as Dale K has rightly pointed out in the request comments: comma-separated joins got replaced by proper joins (INNER JOIN, LEFT OUTER JOIN etc.) in 1992. You should not use that ancient syntax anymore.
You could use a union query:
SELECT Name FROM students WHERE No = 4
UNION ALL
SELECT pchar
FROM (SELECT TOP 1 pchar FROM pcharacter ORDER BY NEWID()) t;
This assumes that both the Name and pchar columns are text, i.e. they have the same type. If not, then we might need some casting to make the above work.
Related
Scenario: Have a table with four columns. District_Number, District_name, Data_Collection_Week, enrollments. Each week we get data, BUT sometimes we do not.
Task: My supervisor wants me to produce a query that will let us know, which districts did not submit a given week.
What I have tried is below, but I cannot get a NULL value on those that did not submit a week.
SELECT DISTINCT DistrictNumber, DistrictName, DataCollectionWeek
into #test4
FROM EDW_REQUESTS.INSTRUCTION_DELIVERY_ENROLLMENT_2021
order by DistrictNumber, DataCollectionWeek asc
select DISTINCT DataCollectionWeek
into #test5
from EDW_REQUESTS.INSTRUCTION_DELIVERY_ENROLLMENT_2021
order by DataCollectionWeek
select b.DistrictNumber, b.DistrictName, b.DataCollectionWeek
from #test5 a left outer join #test4 b on (a.DataCollectionWeek = b.DataCollectionWeek)
order by b.DistrictNumber, b.DataCollectionWeek asc
One option uses a cross join of two select distinct subqueries to generate all possible combinations of districts and weeks, and then not exists to identify those that are not available in the table:
select d.districtnumber, w.datacollectionweek
from (select distinct districtnumber from edw_requests.instruction_delivery_enrollment_2021) d
cross join (select distinct datacollectionweek from edw_requests.instruction_delivery_enrollment_2021) w
where not exists (
select 1
from edw_requests.instruction_delivery_enrollment_2021 i
where i.districtnumber = d.districtnumber and i.datacollectionweek = w.datacollectionweek
)
This would be simpler (and much more efficient) if you had referential tables to store the districts and weeks: you would then use them directly instead of the select distinct subqueries.
I have a table with multiple data for same ID. I want to get the first row data for the ID.
I have added the below SQL that I have tried.
SELECT
"client"."id",
"client"."company_name",
"client_details"."address"
from Client
LEFT OUTER JOIN "client_details" ON ("client"."id" = "client_details"."client_id")
Since I have multiple address for the same ID, can we get only the first id?
Currently the output I get is 2 rows with different addresses.
You can add to your SQL LIMIT 1 and in case you want to be sure the order you can also add to your SQL ORDER BY...
You can use distinct on:
select distinct on (c.id) c.id, c.company_name, cd.address
from Client c left join
client_details cd
on c.id = cd.client_id
order by c.id, ?;
The ? is for the column that specifies the ordering (the definition of "first"). I am guessing that cd.id is what you want.
Note that this query removes the double quotes and introduces table aliases. This is easier on both the eyes (to read) and the fingers (to type).
use row_number()
select * from
(
SELECT
"client"."id",
"client"."company_name",
"client_details"."address",row_number() over(partition by "client"."id" order by "client_details"."address") as rn
from Client
LEFT OUTER JOIN "client_details" ON "client"."id" = "client_details"."client_id"
)A where rn=1
If there is a field you can order the results by you could use a lateral join e.g.
SELECT
"client"."id",
"client"."company_name",
"client_details"."address"
from Client
left join lateral (
select *
from client_details cd
where cd.client_id = client.id
order by [some_ordering_field]
limit 1
) "client_details" on true
I am trying to query some data from SQL Server 2012 using sub query. I am trying to get first 3 records for each Id returned by Sub Query but I am not getting the idea how to do so for now I write this query:
Select * from Student Where TeacherId in (Select TeacherId from Teacher)
I am not sure if this is achievable by using such query or do I have to write a function or any thing else ?
Any Suggestions would be great and sorry for my bad explanation skills.
You should join the Teacher to Student table, and then use an analytic function to get the first there records for each teacher:
SELECT *
FROM
(
SELECT
s.*, t.TeacherId, t.TeacherName,
ROW_NUMBER() OVER (PARTITION BY t.TeacherId ORDER BY some_col) rn
FROM Teacher t
INNER JOIN Student s
ON t.TeacherId = s.TeacherId
) t
WHERE rn = 3;
I assume that there is a column in one of the two tables some_col which you want to use for ordering. It does not make much sense to speak of the first three records without also defining some ordering.
I guess you want the top 3 rows for each ids, not top 3 rows for entire result set
WITH CTE AS
(
SELECT *,
ROW_NUMBER() OVER (PARTITION BY t.TeacherId ORDER BY ?) Seq
FROM Student s
INNER JOIN Teacher t ON t.TeacherId = s.TeacherId
)
SELECT * FROM CTE
WHERE Seq between 1 AND 3
? placeholder requires column_name to generate the sequence_number to get the result with boundary of 1 to 3 .
I need to limit the results of my query so that it only pulls results where the total number of lines on the ID is less than 4, and am unsure how to do this without losing the select statement columns.
select fje.journalID, fjei.ItemID, fjei.acccount, fjei.debit, fjei.credit
from JournalEntry fje
inner join JournalEntryItem fjei on fjei.journalID = fje.journalID
inner join JournalEntryItem fjei2 on fjei.journalID = fjei2.journalID and
fjei.ItemID != fjei2.ItemID
order by fje.journalID
So if journalID 1 has 5 lines, it should be excluded, but if it has 4 lines, I should see it in my query. Just need a push in the right direction. Thanks!
A subquery with an alias has many names, but it's effectively a table. In your case, you would do something like this.
select your fields
from your tables
join (
select id, count(*) records
from wherever
group by id ) derivedTable on someTable.id = derivedTable.id
and records < 4
Can someone help explain to me how when I have 12 rows in table A and 10 in B and I do an inner join , I would get more rows than
in both A and B ?
Same with left and right joins...
This is just a simplified example. Let me share one of my issues with you
I have 2 views ; which was originally SQL on 2 base tables Culture and Trials.
And then when attempting to add another table Culture Steps, one of the team members separated the SQL into 2 views
Since this produces an error when updating(modification cannot be done as it affects multiple base tables), I would like to get
back to changing the SQL such that I no longer use the views but achieve the same results.
One of the views has
SELECT some columns
FROM dbo.Culture RIGHT JOIN
dbo.Trial ON dbo.Culture.cultureID = dbo.Trial.CultureID LEFT OUTER JOIN
dbo.TrialCultureSteps_view_part1 ON dbo.Culture.cultureID = dbo.TrialCultureSteps_view_part1.cultureID
The other TrialCultureSteps_view_part1 view
SELECT DISTINCT dbo.Culture.cultureID,
(SELECT TOP (1) WeekNr
FROM dbo.CultureStep
WHERE (CultureID = dbo.Culture.cultureID)
ORDER BY CultureStepID) AS normalstartweek
FROM dbo.Culture INNER JOIN
dbo.CultureStep AS CultureStep_1 ON dbo.Culture.cultureID = CultureStep_1.CultureID
So how can I combine the joins the achieve the same results using SQL only on tables without the need for views?
Welcome to StackOverflow! This link might be a good place to start in your understanding of JOINs. Essentially, the 'problem' you describe boils down to the fact that one or more of your sources (Trial, Culture, or the TrialCultureSteps view) has more than one record per CultureID - in other words, the same CultureID (#1) shows up on multiple rows.
Based solely on that ID, I'd execute the following three queries. Anything that is returned by them is the 'cause' of your duplications - the culture ID shows up more than once, so you'll have to JOIN on more than just CultureID. If, as I half-suspect, your view is the one that has multiple Culture IDs, you'll need to modify it to only return one record, or change the way that you JOIN to it.
SELECT *
FROM Trial
WHERE CultureID IN
(
SELECT CultureID
FROM Trial
GROUP BY CultureID
HAVING COUNT(*) > 1
)
ORDER BY CultureID
SELECT *
FROM Culture
WHERE CultureID IN
(
SELECT CultureID
FROM Culture
GROUP BY CultureID
HAVING COUNT(*) > 1
)
ORDER BY CultureID
SELECT *
FROM TrialCultureSteps_view_part1
WHERE CultureID IN
(
SELECT CultureID
FROM TrialCultureSteps_view_part1
GROUP BY CultureID
HAVING COUNT(*) > 1
)
ORDER BY CultureID
Let me know if any of these return values!
The comments explain the JOIN issues. As for rewriting, any views could be replaced with CTEs.
One other way to rewrite the query, would be : (Though having sample data and expected result would make this easier to confirm that it's correct)
;with TrialCultureSteps_view_part1 AS
(
Select Row_number() OVER (Partition BY CultureID ORDER BY CultureStepID) RowNumber
, WeekNr
, CultureID
)
SELECT some columns
dbo.trial LEFT OUTER JOIN
dbo.Culture ON dbo.Culture.cultureID = dbo.Trial.CultureID LEFT OUTER JOIN
TrialCultureSteps_view_part1 ON dbo.Culture.cultureID = dbo.TrialCultureSteps_view_part1.cultureID and RowNumber=1
Access code, I'm less familiar with the syntax, but I know that Row_Number() isn't available and I don't believe it has CTE syntax either. So, we'd need to put in some more nested derived tables.
SELECT some columns
dbo.trial LEFT OUTER JOIN
dbo.Culture ON dbo.Culture.cultureID = dbo.Trial.CultureID LEFT OUTER JOIN
( Select cs.CultureID, cs.WeekNr FROM
( SELECT CultureID, MIN(CultureStepID) CultureStepID
FROM dbo.CultureStep
GROUP BY CultureID
) Fcs INNER JOIN
CultureStep cs ON fcs.cultureStepID=cs.CultureStepID
) TrialCultureSteps_view_part1 ON dbo.Culture.cultureID = TrialCultureSteps_view_part1.cultureID
Assumptions here, is that CultureStepID is a PK for CultureStep. No assumption that a step must exist for each Culture entry.