I have a table
id date state
1 10.01.01 reg
2 08.01.01 reg
3 05.01.01 check
4 02.01.01 check
5 01.01.01 reg
and want to show result like this
count reg
5 1
e.g sum of "reg" statuses should be counted only if the previous status was "check".
Please, help me or give the right direction to solve it
In SQL Server 2012 and above you could use LAG to access the previous row value:
SQL SERVER 2012
;WITH MyCTE AS
(
select id, date,state,lag(state,1) over(order by id) as prevstate
from Table1
)
SELECT COUNT(*),SUM(CASE WHEN state = 'reg' AND prevstate = 'check' THEN 1 ELSE 0 END)
FROM MyCTE
Fiddler Demo
ORACLE
With T AS
(
select "id", "date", "state", lag("state",1) over(order by "id") as "prevstate"
from Table1
)
SELECT COUNT(*),SUM(CASE WHEN "state" = 'reg' AND "prevstate" = 'check' THEN 1 ELSE 0 END)
FROM T
Fiddler Demo
MySQL
SELECT COUNT(*),SUM(CASE WHEN state = 'reg' AND prevstate = 'check' THEN 1 ELSE 0 END)
FROM
(
SELECT T1.ID,T1.Date,T1.state,T2.state AS prevstate
FROM Table1 T1
LEFT JOIN Table1 T2
ON T1.ID - 1 = T2.ID
) AS T
Fiddler Demo
Actually the third case would work in prety much everything.
Related
I Have in table some records:
ID Services
2 A
2 C
2 C1
2 D2
I`m trying make query that will be select a link between services.
For example: If for ID 2 exists Services C then check if exist Service C1, result Yes or No.
SELECT a. ID, a.service,
CASE
WHEN (a.service ='C') = (a.service = 'C1') THEN 'Yes'
ELSE 'No'
END
FROM t1 a
Try this query:
SELECT *
FROM yourTable t1
WHERE NOT EXISTS (SELECT 1 FROM yourTable t2
WHERE (t2.Services LIKE t1.Services + '%' OR
t1.Services LIKE t2.Services + '%') AND
t1.ID = t2.ID AND t1.Services <> t2.Services);
This returns A and D2 only.
Demo
Hmm... what about this? But I now have problem with checking relationship for each ID independently...
SELECT a. ID, a.service,
CASE
WHEN a.service IN ('C','C1') THEN 'Yes'
ELSE 'No'
END
FROM t1 a
If I understand correctly, you can use aggregation:
SELECT ID,
(CASE WHEN SUM(CASE WHEN service = 'C' THEN 1 ELSE 0 END) > 0 AND
SUM(CASE WHEN service = 'C1' THEN 1 ELSE 0 END) > 0
THEN 'Yes' ELSE 'No'
END) as c_c1_flag
FROM t1
GROUP BY ID;
The SUM(CASE . . . ) counts the number of rows that match the conditions. The > 0 simply says that at least one row exists.
I am have a table with data and now i need to return zero in select statement if there is no records in table for example. I need to use it in Stored Procedure.
-- If no records exists in below select statement
SELECT ID,Text,Date FROM tblData WHERE ID = 12
IF (##ROWCOUNT = 0)
BEGIN
SELECT -5 AS ID
END
Output:
ID Text Date
ID
-5
Expected output
ID
-5
If you want to return 1 row even when there is no match, you can use aggregation:
SELECT (CASE WHEN COUNT(*) = 0 THEN -5 ELSE MAX(ID) END) as ID
FROM tblData
WHERE ID = 12;
I always use an Exists statment.
if exists(SELECT ID FROM tblData WHERE ID = 12)
select 0 as RowsExist
else
select 1 as RowsExist
For a single scalar value you could use something like;
SELECT ISNULL((SELECT ID FROM tblData WHERE ID = 12), 0) as ID
Rhys
SELECT (CASE WHEN Ta.ID IS NULL THEN TBL.ID
ELSE Ta.ID END) AS ID,Ta.Text,Ta.Date
FROM (VALUES(-5)) AS TBL(ID)
LEFT JOIN
(
SELECT ID,Text,Date FROM tblData WHERE ID = 12
)
AS Ta ON Ta.ID = Ta.ID
I have a token table
id | status
------------
1 | taken
1 | used
1 | deleted
2 | taken
2 | deleted
3 | taken
I need to count how many tokens are used ( in use or used).
If a token is taken and deleted without being used then it should not be counted.
So sql would be sth like
SELECT count(*) if the id's status is not (taken & deleted)
The desired number of used token in above example is 2 as
id 1 has been taken used and deleted -> count it
id 3 has been taken -> count it
id 2 has been taken and deleted without being used -> do not count it
A little bit verbose but efficient and still readable and maintainable:
SELECT COUNT(DISTINCT id)
FROM dbo.Token t
WHERE EXISTS
(
SELECT 1 FROM dbo.Token t1
WHERE t.id = t1.id
AND t1.status = 'used'
)
OR
(
EXISTS(
SELECT 1 FROM dbo.Token t1
WHERE t.id = t1.id
AND t1.status = 'taken'
)
AND NOT EXISTS(
SELECT 1 FROM dbo.Token t1
WHERE t.id = t1.id
AND t1.status = 'deleted'
)
)
Demo
Use aggregation and a having clause to get the list of eligible ids:
SELECT id
FROM token t
GROUP BY id
HAVING SUM(case when status = 'taken' then 1 else 0 end) > 0 or
SUM(case when status = 'used' then 1 else 0 end) > 0;
To get the count, use a subquery or CTE:
SELECT COUNT(*)
FROM (SELECT id
FROM token t
GROUP BY id
HAVING SUM(case when status = 'taken' then 1 else 0 end) > 0 or
SUM(case when status = 'used' then 1 else 0 end) > 0
) t
Try this:
SELECT SUM(CASE WHEN (CHARINDEX('used', data.status) > 0) OR (data.status = 'taken') THEN 1 ELSE 0 END) as [count]
FROM
(
SELECT DISTINCT id, (SELECT STUFF((SELECT Distinct ',' + status
FROM token a
WHERE a.id = b.id
FOR XML PATH (''))
, 1, 1, '')) as status
FROM token b
) data
Demo
You need to be able to take into account all three conditions, so a naive approach would be to just compare each three with a case statement:
WITH grouped as
(
select id from #uses group by id
)
select grouped.id,
used =
CASE WHEN used.id is not null THEN 'YES'
WHEN taken.id is not null and deleted.id is null THEN 'YES'
ELSE 'NO'
END
from grouped
left join #uses taken on grouped.id = taken.id
and taken.use_status = 'taken'
left join #uses used on grouped.id = used.id
and used.use_status = 'used'
left join #uses deleted on grouped.id = deleted.id
and deleted.use_status = 'deleted'
The case statement will stop whenever the condition is met, so you only need to WHEN's and an ELSE to meet the conditions.
This is a naive approach, though, and assumes that you only ever have one row per id and use status type. You'd have to do some additional work if that wasn't the case.
if token has been taken and used -> do not count it
SELECT
SUM(DECODE(status, 'taken', 1, 0)) +
SUM(DECODE(status, 'used', 1, 0)) -
SUM(DECODE(status, 'deleted', 1, 0))
FROM
token t
WHERE
status <> 'used' OR
EXISTS(SELECT 1 FROM token t2 WHERE t2.id = t.id and t2.status = 'deleted')
if token has been taken and used -> count it
SELECT
COUNT(1)
FROM
token t
WHERE
status = 'taken' AND
(
EXISTS(SELECT 1 FROM token t2 WHERE t2.id = t.id and t2.status = 'used') OR
NOT EXISTS(SELECT 1 FROM token t2 WHERE t2.id = t.id and t2.status = 'deleted')
)
Coming back to this question, one solution could be with using Pivot
SELECT COUNT(id)
FROM (
SELECT id, status FROM Token
) src
PIVOT
(
COUNT(status) FOR status IN ([taken], [used], [deleted])
) pvt
WHERE (taken = 1 AND deleted = 0)OR (used = 1)
DEMO
I would like to SUM() while also using a WHERE but when there are no records found for a certain ID I would like it to return NULL instead of just not returning anything.
Initial Code:
SELECT
ID,
SUM(CASE WHEN EVENTS = 3 THEN 1 ELSE 0 END)
FROM Events_ID
WHERE
YEAR = 2012
GROUP BY ID
This would not return an ID if there were no events for it in 2012.
I then changed it to the following that appears to work but is around 100x slower!
SELECT
ID,
(SELECT
SUM(CASE WHEN EVENTS = 3 THEN 1 ELSE 0 END)
FROM EVENTS_ID r WHERE r.ID = t.ID AND r.YEAR = 2012)
FROM (SELECT * FROM Events_ID GROUP BY ID) as t;
Is there anyway to get the output of the second query nearer to the speed of the first?
Is this what you want?
SELECT ID,
SUM(CASE WHEN EVENTS = 3 AND YEAR = 2012 THEN 1 END)
FROM Events_ID
GROUP BY ID;
This will return all ids, with a NULL as a second value if no events match both conditions.
I have a sql select query that extracts result as:
login_count login_type
2000 iPhone
7000 browser
But i want the result as:
iphone_login browser_login
2000 7000
i.e. i want to extract row1-col1 as col1 and row2-col2 as col2 using a select query.
My original query is
select count(login_count), login_type from log_table group by login_type;
Thanks,
Gaurav
Try this:
SELECT
SUM( IF(login_type = 'iPhone', 1, 0) ) AS iphone_login,
SUM( IF(login_type = 'browser', 1, 0) ) AS browser_login
FROM log_table
Here is another option that works in MySQL and in other dbms as well.
select sum(case when login_type = 'iPhone' then 1 else 0 end) as iphone_login
,sum(case when login_type = 'browser' then 1 else 0 end) as browser_login
from log_table