Question

Need help on sql(mysql query) to check that the selected ‘startdate’ and ‘enddate’ does not have any records in that range.

bellow is my table :

---------------------------------------------------------
| id |    start           |     end            |activity|
---------------------------------------------------------
| 1  |2011-10-30 13:00:00 |2011-10-30 14:00:00 | study  |
| 2  |2011-10-30 15:00:00 |2011-10-30 16:00:00 | tennis |
| 3  |2011-10-30 17:00:00 |2011-10-30 18:00:00 | golf   |
| 4  |2011-10-30 18:00:00 |2011-10-30 19:00:00 | gym    |
| 5  |2011-10-30 20:00:00 |2011-10-30 21:00:00 | study  |
---------------------------------------------------------

i hope this post will be usefull for others as well.The start and end columns are datetime data type.Basically the query that i am trying to do is to check for activity clashing.

need help .thank you in advance.

Answer 1

Basically you need to see if either the start or the end date of one record is inside another row’s start and end dates. I did it with an INNER JOIN. You could also do it with a WHERE' clause instead.

Select [your fields]
From table t1
           Inner join table t2
           On t1.id <> t2.id
               And (( t1.start > t2.start
                    And t1.start < t2.end)
                     Or
                    (t1.end > t2.start
                    And t1.end < t2.end))