Converting string to datetime problem - sql

Question

Using SQL Server 2000:
SELECT PERSONID,
CARDEVENTDATE,
INTIME,
CASE
WHEN OUTTIME = INTIME THEN
'No PunchOut'
ELSE
OUTTIME
END AS OUTTIME,
CONVERT(char(8), CASE
WHEN DateAdd(Day, - DateDiff(Day, 0, OutTime), OutTime) > '18:00:00' THEN
Cast('18:00:00' AS datetime)
ELSE
DateAdd(Day, - DateDiff(Day, 0, OutTime), OutTime)
END - CASE
WHEN DateAdd(Day, - DateDiff(Day, 0, InTime), InTime) < '09:00:00' THEN
Cast('09:00:00' AS datetime)
ELSE
DateAdd(Day, - DateDiff(Day, 0, InTime), InTime)
END, 8) AS WorkTime
FROM (SELECT T_PERSON.PERSONID,
T_CARDEVENT.CARDEVENTDATE,
MIN(T_CARDEVENT.CARDEVENTTIME) AS INTIME,
MAX(T_CARDEVENT.CARDEVENTTIME) AS OUTTIME
FROM T_PERSON
INNER JOIN T_CARDEVENT ON T_PERSON.PERSONID = T_CARDEVENT.PERSONID
GROUP BY T_PERSON.PERSONID, T_CARDEVENT.CARDEVENTDATE) DERIVEDTBL
T_cardevent.cardeventtime column datatype is Varchar.
In table Cardeventtime values are 080002, 091235.... so on...,
When I executing the above query it showing Arithmetic Express Overflow error for converting expression to datatype Datetime.

Answer 1

So this "080002" stands for? 8 hours, 0 minutes, 2 seconds?
This is definitely not a valid DATETIME format out of the box - and it doesn't comply with any of the valid SQL Server CONVERT styles, either.
So you'll have to do some conversions yourself, manually. Is there any chance you could wrap the table with this column into a view which could handle the conversion?
You'd have to do something along the lines of:
CONVERT(DATETIME, SUBSTRING(CardEventTime, 1, 2) + ':' +
SUBSTRING(CardEventTime, 3, 2) + ':' +
SUBSTRING(CardEventTime, 5, 2), 8)
and this should turn your "080002" into "08:00:02" which can then be converted to a DATETIME (no separate time datatype until SQL Server 2008) using the style no. 8 (hh:mm:ss).
Marc

Answer 2

I've made a series of assumptions here, and worked without being able to test it, but here's a possible solution:
SELECT PERSONID,
CARDEVENTDATE,
INTIME,
CASE
WHEN OUTTIME = INTIME THEN
'No PunchOut'
ELSE
OUTTIME
END AS OUTTIME,
Stuff(Stuff(Right('000000' +
CONVERT(varchar(5), CASE
WHEN Convert(int,OutTime) > 180000 THEN
180000
ELSE
Convert(int,OutTime)
END - CASE
WHEN Convert(int,InTime) < 90000 THEN
90000
ELSE
Convert(int,InTime)
END), 6),5,0,':'),3,0,':')
AS WorkTime
FROM (SELECT T_PERSON.PERSONID,
T_CARDEVENT.CARDEVENTDATE,
MIN(T_CARDEVENT.CARDEVENTTIME) AS INTIME,
MAX(T_CARDEVENT.CARDEVENTTIME) AS OUTTIME
FROM T_PERSON
INNER JOIN T_CARDEVENT ON T_PERSON.PERSONID = T_CARDEVENT.PERSONID
GROUP BY T_PERSON.PERSONID, T_CARDEVENT.CARDEVENTDATE) DERIVEDTBL
I've not used Stuff very frequently, so the insertion points may be off.