Question

I am trying to write a Microsoft SQL Server query for retrieving the oldest record in which the text fields are the same, but the dates are 30 seconds or less apart. Here is an example:

My table:

RecordID     TextField1              TextField2           DateField1
--------------------------------------------------------------------------------
1            SomeData1               SomeData2            9/11/2011 2:33:00pm
2            SomeData3               SomeData4            9/11/2011 2:33:15pm
3            SomeData3               SomeData4            9/11/2011 2:33:18pm
4            SomeData3               SomeData4            9/11/2011 2:42:12pm
5            SomeData1               SomeData2            9/11/2011 2:33:01pm
6            SomeData6               SomeData7            9/11/2011 2:33:01pm
7            SomeData1               SomeData2            9/12/2011 2:33:00pm
8            SomeData6               SomeData8            9/11/2011 2:33:03pm

Okay, so in this example, I want a query that will pull the rows in which TextField1=TextField1 and TextField2=TextField2 and the dates between them are 30 seconds or less (I want the oldest of the two returned). So the query, in this example, should return:

RecordID     TextField1              TextField2           DateField1
--------------------------------------------------------------------------------
1            SomeData1               SomeData2            9/11/2011 2:33:00pm
2            SomeData3               SomeData4            9/11/2011 2:33:15pm

RecordID 8 is not returned because TextField2 is different.

Hopefully I explained this clearly enough. Any help would be appreciated!

Answer 1

I couldn’t understand everything on your question.

This is a generic SQL query that will compare the records of you table, against the same table, looking for records with different RecordID, but equal TextField1 and TextField2.

Leave a comment if this looks like what you want and we can improve this query to get exactly what you are looking for.

UPDATED:

SELECT * FROM my_table AS t1
INNER JOIN my_table AS t2
ON (
    t1.RecordID < t2.recordID
    AND
    DATEDIFF(second, t1.DateField1, t2.DateField1) <= 30
    AND
    t1.TextField1 = t2.TextField1
    AND
    t2.TextField2 = t1.TextField2
);