Question

I have two queries. The first query:

select in_gentime
from in_time_temp
where cardnumber = 'MCL1570'
order by in_gentime

Output is:

2011-10-11 08:06:00.000
2011-10-12 08:35:00.000
2011-10-13 08:21:00.000
2011-10-15 08:21:00.000
2011-10-16 08:21:00.000
2011-10-17 08:21:00.000
2011-10-18 08:21:00.000
2011-10-19 08:21:00.000
2011-10-20 08:21:00.000
2011-10-21 08:21:00.000
2011-10-22 08:21:00.000
2011-10-24 08:21:00.000
2011-10-25 08:21:00.000
2011-10-26 09:00:00.000
2011-10-27 09:00:00.000
2011-10-28 09:00:00.000
2011-10-29 09:00:00.000
2011-10-31 09:00:00.000

The second query:

select out_gentime
from out_time_temp
where cardnumber = 'MCL1570'
order by out_gentime

Output is:

2011-10-11 22:02:00.000
2011-10-12 21:14:00.000
2011-10-14 21:59:00.000
2011-10-15 21:59:00.000
2011-10-16 21:59:00.000
2011-10-17 21:59:00.000
2011-10-18 21:59:00.000
2011-10-19 21:59:00.000
2011-10-20 21:59:00.000
2011-10-21 21:59:00.000
2011-10-22 21:59:00.000
2011-10-24 21:59:00.000
2011-10-25 21:59:00.000
2011-10-26 18:15:00.000
2011-10-27 18:15:00.000
2011-10-28 18:15:00.000
2011-10-29 23:15:00.000
2011-10-31 22:15:00.000

I need to identify records that have DATE values that appear in one table but not the other. I want to ignore the specific TIME. For example, I want to only return these 2 records:

2011-10-13 08:21:00.000
2011-10-14 21:59:00.000 

How can I write a query to do this?

Answer 1

If you use a FULL OUTER JOIN, you can join together the list of dates and then just pick the records where one or the other is NULL:

SELECT COALESCE(i.in_gentime, o.out_gentime)  -- pick first non-null value
FROM in_time_temp i
FULL OUTER JOIN out_time_temp o 
    ON  CAST(CONVERT(varchar(8), i.in_gentime,  112) AS datetime) = 
        CAST(CONVERT(varchar(8), o.out_gentime, 112) AS datetime)
    AND i.cardnumber = o.cardnumber
WHERE (i.in_gentime is null or o.out_gentime IS NULL)
AND   (i.cardnumber = 'MCL1750' OR o.cardnumber = 'MCL1750')

Update. Nathan, here is the full test code, I’m not sure why you are not getting results, but this returns 4 records when I run it:

CREATE TABLE in_time_temp  
(
    in_gentime   datetime,
    cardnumber   nvarchar(50)
)
insert into in_time_temp values('2011-10-11 08:06:00.000', 'MCL1750')
insert into in_time_temp values('2011-10-12 08:35:00.000', 'MCL1750')
insert into in_time_temp values('2011-10-13 08:21:00.000', 'MCL1750')
insert into in_time_temp values('2011-10-15 08:21:00.000', 'MCL1750')
insert into in_time_temp values('2011-10-16 08:21:00.000', 'MCL1750')
insert into in_time_temp values('2011-10-17 08:21:00.000', 'MCL1750')


CREATE TABLE out_time_temp
(
    out_gentime    datetime,
    cardnumber   nvarchar(50)
)
insert into out_time_temp values('2011-10-11 22:02:00.000', 'MCL1750')
insert into out_time_temp values('2011-10-12 21:14:00.000', 'MCL1750')
insert into out_time_temp values('2011-10-14 21:59:00.000', 'MCL1750')
insert into out_time_temp values('2011-10-15 21:59:00.000', 'MCL1750')
insert into out_time_temp values('2011-10-16 21:59:00.000', 'MCL1750')
insert into out_time_temp values('2011-10-17 21:59:00.000', 'MCL1750')
insert into out_time_temp values('2011-10-18 21:59:00.000', 'MCL1750')
insert into out_time_temp values('2011-10-19 21:59:00.000', 'MCL1750')


SELECT COALESCE(i.in_gentime, o.out_gentime)  -- pick first non-null value
FROM in_time_temp i
FULL OUTER JOIN out_time_temp o 
    ON  CAST(CONVERT(varchar(8), i.in_gentime,  112) AS datetime) = 
        CAST(CONVERT(varchar(8), o.out_gentime, 112) AS datetime)
    AND i.cardnumber = o.cardnumber
WHERE (i.in_gentime is null or o.out_gentime IS NULL)
AND   (i.cardnumber = 'MCL1750' OR o.cardnumber = 'MCL1750')

And the output is:

2011-10-13 08:21:00.000
2011-10-14 21:59:00.000
2011-10-18 21:59:00.000
2011-10-19 21:59:00.000