How i can remove results of my Query, using LAG function? - sql

Question

First of all, srry for my bad english.
I need to calculate the iddle time of an separators group. Actualy i have the following query:
USE mydatabase
SELECT p.iddoc as SaleOrder, p.name as Client, u.username as SysUser,
CONVERT(DATETIME, o.creatdate) as CreateDate,
CONVERT(DATETIME, o.inidate) as IniDate,
CONVERT(DATETIME, o.findate) as FinalDate,
RIGHT('0' + CAST(DATEDIFF(S, (lag(o.findate, 1) OVER (ORDER BY o.findate)), o.inidate) / 3600 AS VARCHAR(2)),2) + ':'
+ RIGHT('0' + CAST(DATEDIFF(S, (lag(o.findate, 1) OVER (ORDER BY o.findate)), o.inidate) % 3600/60 AS VARCHAR(2)),2) + ':'
+ RIGHT('0' + CAST(DATEDIFF(S, (lag(o.findate, 1) OVER (ORDER BY o.findate)), o.inidate) % 60 AS VARCHAR(2)),2) as IdleTime
FROM serviceorder o
inner join user u on o.usercode = u.codusuario
inner join requests p on o.idrequest = p.codpedidocab
WHERE u.username like ('USER NAME')
and o.iduserstart is NOT NULL
and p.sit = '8'
and o.creatdate BETWEEN '2020-06-30 00:00:00' and '2020-06-30 23:59:00'
and o.inidate BETWEEN '2020-06-30 00:00:00' and '2020-06-30 23:59:00'
ORDER BY o.inidate
My problem on this query is when "o.inidate is < than a last o.findate", i need to remove the results than have "o.inidate < (lag(o.findate, 1) OVER (ORDER BY o.findate))", but i can't this because can't use the LAG on the where.
What do you suggest i do?

Answer 1

Window functions can be used in the select and order by clauses only. You can use a subquery instead:
SELECT *
FROM (
SELECT
p.iddoc as SaleOrder,
p.name as Client,
u.username as SysUser,
CONVERT(DATETIME, o.creatdate) as CreateDate,
CONVERT(DATETIME, o.inidate) as IniDate,
CONVERT(DATETIME, o.findate) as FinalDate,
LAG(o.findate) OVER (ORDER BY o.findate) lagFinalDate,
RIGHT('0' + CAST(DATEDIFF(S, (lag(o.findate, 1) OVER (ORDER BY o.findate)), o.inidate) / 3600 AS VARCHAR(2)),2) + ':'
+ RIGHT('0' + CAST(DATEDIFF(S, (lag(o.findate, 1) OVER (ORDER BY o.findate)), o.inidate) % 3600/60 AS VARCHAR(2)),2) + ':'
+ RIGHT('0' + CAST(DATEDIFF(S, (lag(o.findate, 1) OVER (ORDER BY o.findate)), o.inidate) % 60 AS VARCHAR(2)),2) as IdleTime
FROM serviceorder o
INNER JOIN [user] u ON o.usercode = u.codusuario
INNER JOIN requests p ON o.idrequest = p.codpedidocab
WHERE
u.username = 'USER NAME'
AND o.iduserstart is NOT NULL
AND p.sit = '8'
AND o.creatdate >= '2020-06-30'
AND o.creatdate < '2020-07-01'
AND o.inidate >= '2020-06-30'
AND o.inidate < '2020-07-01'
) t
where IniDate < lagFinalDate
Additional changes to the query:
half-open interval filters are more accurate (and easier to understand) than between
u.username like ('USER NAME') is equivalent to u.username = 'USER NAME'
user is a language keyword, hence it needs to be quoted when used as a table name