since I am not as good with more complex SQL SELECT Statements I thought of just asking here, since it's hard to find something right on topic.
I got two tables who have exactly the same structure like
TABLE A (id (INT(11)), time (VARCHAR(10));)
TABLE B (id (INT(11)), time (VARCHAR(10));)
Now I want a single SELECT to count the entrys of an specific id in both tables.
SELECT COUNT(*) FROM TABLE A WHERE id = '1';
SELECT COUNT(*) FROM TABLE B WHERE id = '1';
So I thought it would be much better for the database performance if I use one SELECT instead of one.
Thanks for helping out
SELECT COUNT(*) as count, 'tableA' as table_name FROM TABLEA WHERE id = '1'
union all
SELECT COUNT(*), 'tableB' FROM TABLEB WHERE id = '1'
If you want the separate counts in a single row, you can use subqueries
SELECT
(SELECT COUNT(*) FROM TABLE A WHERE id = '1') a_count,
(SELECT COUNT(*) FROM TABLE B WHERE id = '1') b_count;
You could do it like:
select count(*)
from (
select id from t1 where id = 1
union all
select id from t2 where id = 1
) as t
Another alternative is:
select sum(cnt)
from (
select count(*) as cnt from t1 where id = 1
union all
select count(*) as cnt from t2 where id = 1
) as t
Related
I have 2 rows
code name
1 cake
2 chocolate
This query give me both results
select * from table a where a.code=2 or a.code =1
If one of these records doesn't show, I don't want to retrieve anything.
select * from table a where a.code=2 or a.code =1
and exists ( select 1 from table b where a.code=b.code )
You can use an analytic function:
SELECT code,
name
FROM (
SELECT a.*,
COUNT(DISTINCT code) OVER () AS num_codes
FROM table_name a
WHERE a.code IN (1,2)
)
WHERE num_codes = 2;
Which, for the sample data:
CREATE TABLE table_name (code, name) AS
SELECT 1, 'cake' FROM DUAL UNION ALL
SELECT 2, 'chocolate' FROM DUAL;
Outputs:
CODE
NAME
1
cake
2
chocolate
If you:
DELETE FROM table_name WHERE code = 1;
And run the query again, it outputs:
CODE
NAME
db<>fiddle here
Simple check the count distict
select * from tab1
where code in (1,2)
and (select count(distinct code) from tab1 where code in (1,2)) = 2;
If you want to discard the case where the table has duplicated rows, e.g. 1,1,2
add an other predicate filter
and (select count(*) from tab1 where code in (1,2)) = 2
I'm working with a dataset - structured like this
I want to exclude all records with ReviewRound being "a" if they have gone through review round "b" - If a set of unique ID's has an associated round "b" review, the round "a" review should not be included.
Some records have not gone to round "b". The issues I'm running into are as a result of there being multiple records for each unique ID.
Ideally this could be done in GoogleBigQuery, if not, filtering through GoogleScripts may also be an option!
Any suggestions would be appreciated!
If a set of unique ID's has an associated round "b" review, the round "a" review should not be included.
If I followed you correctly, you could express this as a not condition with a correlated subquery that ensures that, if the current record has ReviewRound = 'a', there is no other record that has the same id and ReviewRound = 'b'.
select t.*
from mytable t
where not (
t.ReviewRound = 'a'
and exists (
select 1
from mytable t1
and t1.id = t.id and t1.ReviewRound = 'b'
)
)
You can do this with window functions as well:
select t.* except (num_bs)
from (select t.*,
countif(reviewround = 'b') over (partition by id) as num_bs
from t
) t
where num_bs = 0 or reviewround = 'b';
By using window functions, you can solve it with this query
SELECT ID, Score
FROM (
SELECT *,
MAX(CASE WHEN ReviewRound = 'b' THEN 1 ELSE 0 END) OVER (partition by ID) as has_b
FROM mytable
) t
WHERE has_b = 0
Re-conceptualizing as keeping only the latest review round, I would try:
select * from mytable join
(select ID, max(ReviewRound) as ReviewRound from mytable group by ID)
on (ID, ReviewRound)
I need the count of this:
select distinct ID
from (
select ID from A
union all
select ID from B
union all
select ID from C
) ids
GROUP BY ID HAVING COUNT(*) > 1;
but I have no idea how to do it.
Use a subquery:
select count(*)
from (select ID
from (select ID from A
union all
select ID from B
union all
select ID from C
) ids
group by ID
having count(*) > 1
) i;
SELECT DISTINCT is almost never needed with GROUP BY and definitely not in this case.
You just want to find the id that appear 2 more times in the A,B,C table, the SQL is below:
select count(1) from (
select
id,
count(1)
from
(
select ID from A
union all
select ID from B
union all
select ID from C
)
group by id having(count(1)>1)
) tmp
I have a table with data similar to below. I am trying to get a list of results that will display all rows where only one unique SourceID exists in status 10. If I were querying this table, I would expect ID's 3 and 4 to be returned.
Table Example
Select *
From table
Where Status = 10 and Source ID in
(
Select SourceID
From Table
Group by SourceID
Having Count(*) = 1
)
You can use NOT EXISTS :
SELECT t.*
FROM table t
WHERE NOT EXISTS (SELECT 1 FROM table t1 WHERE t1.SourceID = t.SourceID AND t1.Status <> t.Status);
Maybe that would work?
SELECT ID FROM Mytable
WHERE [Status] = 10
GROUP BY ID
HAVING COUNT(SourceID) = 1
First, find out all the unique SourceIDs
SELECT
SourceID
FROM
Data
GROUP BY
SourceID
HAVING
COUNT(SourceID) = 1
And then use this query as a sub query to get all the rows that has unique SourceID;
SELECT
*
FROM
Data
WHERE
SourceID IN (
SELECT
SourceID
FROM
Data
GROUP BY
SourceID
HAVING
COUNT(SourceID) = 1
)
Use a sub-query to check if t there is an exact count of 1 of those source id's
SELECT t.* FROM YourTable t WHERE t.status = 10
AND
(SELECT COUNT(0) x From YourTable t2
where t2.sourceid = t.sourceid) = 1
I have different simple SQL request that return only one value. Example
SELECT COUNT(*) FROM Person
OR
SELECT COUNT(*) FROM Category
I would to get all these infos in a unique request, with a column by request...
I tried something like that but it doesn't work :
SELECT COUNT(C.CategoryId) As nbPeople, COUNT(P.PersonID) As nbCategories FROM Category C, Person P
This works but I get only one column, and a row by request
SELECT COUNT(*) FROM Person UNION SELECT COUNT(*) FROM Category
How Can I simply do that ?
Thanks
When using SQL Server, you can try this:
SELECT ( select COUNT(C.CategoryId)
from Category C
) As nbPeople
, ( select COUNT(P.PersonID)
from Person P
) As nbCategories
In Oracle for example, you need to add this at the bottom
FROM dual
You can use UNION ALL like following:
SELECT '' AS [StatisticName], 1 AS [StatisticCount]
WHERE 1=0
UNION ALL
SELECT 'PersonCount', COUNT(*) FROM [Person]
UNION ALL
SELECT 'CathegoryCount', COUNT(*) FROM [Category]
First select with WHERE 1=0 is for create column header names only and is not necessary.
Try this.
select * from
(select count(*) cnt1
from Table1) t1
join
(select count(*) as cnt2
from Table2) t2 on 1=1