How Compare two columns of Same SQL table to find duplicate records

Question

I have one table with two columns:

StartDateTime
EndDateTime

What will be best query to find out which rows has same (StartDateTime, EndDateTime)?

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Answer 1

You did not specify a particular RDBMS (SQL Server, Oracle, etc.), but here is a quick solution that would probably work on most.

Assuming your table has some kind of unique key (primary key - like ID) to determine the difference between one row and another row, you could use a correlated exists check.

SELECT a.*
FROM table1 a
WHERE EXISTS (
 SELECT *
 FROM table1
 WHERE StartDateTime = a.StartDateTime
 AND EndDateTime = a.EndDateTime
 AND Id <> a.Id
 )