For example, i have a table with the data:
Screenshot
This table named "table".
I have the SQL query:
select
kind,
count(kind)
from table
where region = 'eng'
group by kind
And I get the result:
Question: how do I write a query that would return all the values that are in the kind field (or any other field that can be in group by)? Even if this value is 0. For the example above, the desired result is
It is mandatory to use group by in the query.
I use a postgresql 10.
Using a conditional aggregation
select
kind,
count(case region when 'eng' then kind end) cnt
from table
group by kind
select
t1.kind,
coalesce(t2.total, 0) total
from
(
select distinct kind from table
) t1
left join
(
select
kind,
count(kind) total
from table
where region = 'eng'
group by kind
)t2
on t1.kind = t2.kind
db fiddle
Related
I have a table CodeResult as follows:
Here we can notice that Code 123 alone has a Code2, that has a value in Result. I want to take a count of distinct Codes that has no values at all in Result. Which means, in this example, I should get 2.
I do not want to use group by clause because it will slow down the query.
Below code gives wrong result:
Select count(distinct code) from CodeResult where Result is Null
One method is two levels of aggregation:
select count(*)
from (select code
from t
group by code
having max(result) is null
) c;
A more clever method doesn't use a subquery. It counts the number of distinct codes and then removes the ones that have a result:
select ( count(distinct code) -
count(distinct case when result is not null then code end )
)
from t;
You simply can't avoid a GROUP BY: In all DBMSs I know, the query plan you get from a:
SELECT DISTINCT a,b,c FROM tab; ,
is the same as the one for:
SELECT a,b,c FROM tab GROUP BY a,b,c;
The following query will return each of the Code values for which there are no corresponding non-NULL values in CodeResult:
select distinct Code
from CodeResult as CR
where not exists
( select 42 from CodeResult as iCR where iCR.Code = CR.Code and iCR.CodeResult is not NULL );
Counting the rows is left as an exercise for the reader.
I have a table where limits were sanctioned to the customer
I am trying to get the output as below picture i.e. total amount sanctioned till particular date
I am trying below code but this sums the total sanction amount
select gam.id, sum(SANCTION_AMOUNT) from gam
join (select ID,ACCOUNT_OPEN_DATE from gam where ACCOUNT_OPEN_DATE between'01-04-2019' and '30-04-2019' AND SCHEME_CODE IN ('SB','CCKLY')) ) action
on( gam.ACCOUNT_OPEN_DATE <=action.ACCOUNT_OPEN_DATE and gam.id=action.cust_id) group by gam.id;
In Oracle, this can be a way:
select id, sanction_amount, scheme_code, account_open_date,
sum(sanction_amount) over (partition BY ID order by account_open_date) as total_sanction_amount
from gam
order by account_open_date
Not sure your database is MySQL or Oracle, But this below script is workable in most of the database. Just adjust the table and column names accordingly.
You can check MySQL DEMO HERE
SELECT *,
(
SELECT SUM(sanction_Amount)
FROM Your_Table B
WHERE B.ID = A.ID
AND B.acc_open_date <= A.acc_open_date
) Total_sanction_Amount
FROM Your_Table A
I have this table called item:
| PERSON_id | ITEM_id |
|------------------|----------------|
|------CP2---------|-----A03--------|
|------CP2---------|-----A02--------|
|------HB3---------|-----A02--------|
|------BW4---------|-----A01--------|
I need an SQL statement that would output the person with the most Items. Not really sure where to start either.
I advice you to use inner query for this purpose. the inner query is going to include group by and order by statement. and outer query will select the first statement which has the most items.
SELECT * FROM
(
SELECT PERSON_ID, COUNT(*) FROM TABLE1
GROUP BY PERSON_ID
ORDER BY 2 DESC
)
WHERE ROWNUM = 1
here is the fiddler link : http://sqlfiddle.com/#!4/4c4228/5
Locating the maximum of an aggregated column requires more than a single calculation, so here you can use a "common table expression" (cte) to hold the result and then re-use that result in a where clause:
with cte as (
select
person_id
, count(item_id) count_items
from mytable
group by
person_id
)
select
*
from cte
where count_items = (select max(count_items) from cte)
Note, if more than one person shares the same maximum count; more than one row will be returned bu this query.
This issue has been discussed before, but none of the answers address my specific problem because I am dealing with different where clauses in the inner and outer selects. This query executed just fine under Sybase, but gives the error in the title of this post when executed under SQL Server. The query is complicated, but the general outline of the query is:
select sum ( t.graduates -
( select sum ( t1.graduates )
from table as t1
where t1.id = t.id and t1.group_code not in ('total', 'others' ) ) )
from table as t
where t.group_code = 'total'
The following describes the situation I am trying to resolve:
all group codes represent races except for 'total' and 'others'
group code 'total' represents the total graduates of all races
however, multi-race is missing, so the race graduate counts may not add up to the total graduate counts
this missing data is what needs to be calculated
Is there anyway to rewrite this using derived tables or joins to get the same results?
Update: I created sample data and 3 solutions to my specific problem (2 influenced by sgeddes). The one that I added involves moving the correlated subquery to a derived table in the FROM clause. Thanks for the help guys!
One option is to put the subquery in a LEFT JOIN:
select sum ( t.graduates ) - t1.summedGraduates
from table as t
left join
(
select sum ( graduates ) summedGraduates, id
from table
where group_code not in ('total', 'others' )
group by id
) t1 on t.id = t1.id
where t.group_code = 'total'
group by t1.summedGraduates
Perhaps a better option would be to use SUM with CASE:
select sum(case when group_code = 'total' then graduates end) -
sum(case when group_code not in ('total','others') then graduates end)
from yourtable
SQL Fiddle Demo with both
If I have a table with columns id, name, score, date
and I wanted to run a sql query to get the record where id = 2 with the earliest date in the data set.
Can you do this within the query or do you need to loop after the fact?
I want to get all of the fields of that record..
If you just want the date:
SELECT MIN(date) as EarliestDate
FROM YourTable
WHERE id = 2
If you want all of the information:
SELECT TOP 1 id, name, score, date
FROM YourTable
WHERE id = 2
ORDER BY Date
Prevent loops when you can. Loops often lead to cursors, and cursors are almost never necessary and very often really inefficient.
SELECT TOP 1 ID, Name, Score, [Date]
FROM myTable
WHERE ID = 2
Order BY [Date]
While using TOP or a sub-query both work, I would break the problem into steps:
Find target record
SELECT MIN( date ) AS date, id
FROM myTable
WHERE id = 2
GROUP BY id
Join to get other fields
SELECT mt.id, mt.name, mt.score, mt.date
FROM myTable mt
INNER JOIN
(
SELECT MIN( date ) AS date, id
FROM myTable
WHERE id = 2
GROUP BY id
) x ON x.date = mt.date AND x.id = mt.id
While this solution, using derived tables, is longer, it is:
Easier to test
Self documenting
Extendable
It is easier to test as parts of the query can be run standalone.
It is self documenting as the query directly reflects the requirement
ie the derived table lists the row where id = 2 with the earliest date.
It is extendable as if another condition is required, this can be easily added to the derived table.
Try
select * from dataset
where id = 2
order by date limit 1
Been a while since I did sql, so this might need some tweaking.
Using "limit" and "top" will not work with all SQL servers (for example with Oracle).
You can try a more complex query in pure sql:
select mt1.id, mt1."name", mt1.score, mt1."date" from mytable mt1
where mt1.id=2
and mt1."date"= (select min(mt2."date") from mytable mt2 where mt2.id=2)