# Concatenate two columns **URL:** \ **Category:** Logstash\ **Created:** [July 10, 2020, 9:16am UTC](https://discuss.elastic.co/t/concatenate-two-columns/240662 "2020-07-10T09:16:01Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Jasmin](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jasmin/32/56586_2.png) [@Jasmin](https://discuss.elastic.co/u/Jasmin)\ **Post date:** [July 10, 2020, 9:16am UTC](https://discuss.elastic.co/t/concatenate-two-columns/240662/1 "2020-07-10T09:16:01Z")
Hi , i want to select only new entries , and i am gonna use last sql value , but in my case i am wokring on shops , so i have two dates , date of creation ( if somebody buy something ) and date of modification ( if somebody buy something and change it after few days ) so in this case i can't put my date of creation \> sql last value , if i concatenate the date of creation and date last modification can give me a new value that can i track ? ---
**Author:** ![Jenni](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jenni/32/29684_2.png) [@Jenni](https://discuss.elastic.co/u/Jenni)\ **Post date:** [July 10, 2020, 9:24am UTC](https://discuss.elastic.co/t/concatenate-two-columns/240662/2 "2020-07-10T09:24:01Z")
The tracking column has to be numeric or a timestamp. What you suggested would be neither. Maybe you could sort your query by `GREATEST( creation_date, modification_date)` and also use that as a tracking column? ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [August 7, 2020, 9:24am UTC](https://discuss.elastic.co/t/concatenate-two-columns/240662/3 "2020-08-07T09:24:03Z")
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