WITH y AS (
WITH x AS (
SELECT * FROM MyTable
)
SELECT * FROM x
)
SELECT * FROM y
Does something like this work? I tried it earlier but I couldn't get it to work.
This question is related to
sql
sql-server
tsql
nested
common-table-expression
These answers are pretty good, but as far as getting the items to order properly, you'd be better off looking at this article http://dataeducation.com/dr-output-or-how-i-learned-to-stop-worrying-and-love-the-merge
Here's an example of his query.
WITH paths AS (
SELECT
EmployeeID,
CONVERT(VARCHAR(900), CONCAT('.', EmployeeID, '.')) AS FullPath
FROM EmployeeHierarchyWide
WHERE ManagerID IS NULL
UNION ALL
SELECT
ehw.EmployeeID,
CONVERT(VARCHAR(900), CONCAT(p.FullPath, ehw.EmployeeID, '.')) AS FullPath
FROM paths AS p
JOIN EmployeeHierarchyWide AS ehw ON ehw.ManagerID = p.EmployeeID
)
SELECT * FROM paths order by FullPath
You can do the following, which is referred to as a recursive query:
WITH y
AS
(
SELECT x, y, z
FROM MyTable
WHERE [base_condition]
UNION ALL
SELECT x, y, z
FROM MyTable M
INNER JOIN y ON M.[some_other_condition] = y.[some_other_condition]
)
SELECT *
FROM y
You may not need this functionality. I've done the following just to organize my queries better:
WITH y
AS
(
SELECT *
FROM MyTable
WHERE [base_condition]
),
x
AS
(
SELECT *
FROM y
WHERE [something_else]
)
SELECT *
FROM x
With does not work embedded, but it does work consecutive
;WITH A AS(
...
),
B AS(
...
)
SELECT *
FROM A
UNION ALL
SELECT *
FROM B
EDIT Fixed the syntax...
Also, have a look at the following example
Nested 'With' is not supported, but you can always use the second With as a subquery, for example:
WITH A AS (
--WITH B AS ( SELECT COUNT(1) AS _CT FROM C ) SELECT CASE _CT WHEN 1 THEN 1 ELSE 0 END FROM B --doesn't work
SELECT CASE WHEN count = 1 THEN 1 ELSE 0 END AS CT FROM (SELECT COUNT(1) AS count FROM dual)
union all
select 100 AS CT from dual
)
select CT FROM A
we can create nested cte.please see the below cte in example
;with cte_data as
(
Select * from [HumanResources].[Department]
),cte_data1 as
(
Select * from [HumanResources].[Department]
)
select * from cte_data,cte_data1
I was trying to measure the time between events with the exception of what one entry that has multiple processes between the start and end. I needed this in the context of other single line processes.
I used a select with an inner join as my select statement within the Nth cte. The second cte I needed to extract the start date on X and end date on Y and used 1 as an id value to left join to put them on a single line.
Works for me, hope this helps.
cte_extract
as
(
select ps.Process as ProcessEvent
, ps.ProcessStartDate
, ps.ProcessEndDate
-- select strt.*
from dbo.tbl_some_table ps
inner join (select max(ProcessStatusId) ProcessStatusId
from dbo.tbl_some_table
where Process = 'some_extract_tbl'
and convert(varchar(10), ProcessStartDate, 112) < '29991231'
) strt on strt.ProcessStatusId = ps.ProcessStatusID
),
cte_rls
as
(
select 'Sample' as ProcessEvent,
x.ProcessStartDate, y.ProcessEndDate from (
select 1 as Id, ps.Process as ProcessEvent
, ps.ProcessStartDate
, ps.ProcessEndDate
-- select strt.*
from dbo.tbl_some_table ps
inner join (select max(ProcessStatusId) ProcessStatusId
from dbo.tbl_some_table
where Process = 'XX Prcss'
and convert(varchar(10), ProcessStartDate, 112) < '29991231'
) strt on strt.ProcessStatusId = ps.ProcessStatusID
) x
left join (
select 1 as Id, ps.Process as ProcessEvent
, ps.ProcessStartDate
, ps.ProcessEndDate
-- select strt.*
from dbo.tbl_some_table ps
inner join (select max(ProcessStatusId) ProcessStatusId
from dbo.tbl_some_table
where Process = 'YY Prcss Cmpltd'
and convert(varchar(10), ProcessEndDate, 112) < '29991231'
) enddt on enddt.ProcessStatusId = ps.ProcessStatusID
) y on y.Id = x.Id
),
.... other ctes
Source: Stackoverflow.com