MS SQL Server Interview Question:

How To Count Duplicated Values in a Column in MS SQL Server?

Submitted by: Administrator

If you have a column with duplicated values, and you want to know what are those duplicated values are and how many duplicates are there for each of those values, you can use the "GROUP BY ... HAVING" clause as shown in the following example. It returns how many duplicated first names in the ggl_team table:

SELECT first_name, COUNT(*) FROM ggl_team
GROUP BY first_name HAVING COUNT(*) > 1
GO<pre>
first_name count(*)
John 5</pre>
So we have "John" as duplicated first name 5 times in the ggl_team table.
Submitted by: Administrator