SQL

Can you expand on what you're trying to do a little more as there are various ways this might work.

You can check for rows where multiple columns have the same value (ie, WHERE col1 = col2).

You can also do a self-join, such as:

SELECT a.employee_id, a.name, b.name as supervisor_name

FROM employees a 

LEFT JOIN employees b

ON a.supervisor_id = b.employee_id

The details depend on exactly what you're wanting to do with a given dataset.

Hi Sana,

Are you talking about finding duplicates in a column?

If so, you can group by that column and count them, and use HAVING COUNT(*) > 1 to find them.

Hope it helps,

-Leon