Query to determine if columns combine to create a unique key

oracle, sql

Solution

Use the `HAVING` clause to easily identify duplicates.

select t.a, t.b, t.c, count(1) 
from my_table t    
group by t.a, t.b, t.c 
having count(1) > 1;

Problem

I'm trying to determine if a set of three columns on a table in Oracle would constitute a unique key and could be used in a 1:1 relationship. If I run this query, and the keys are a unique combination, I should not see a `count` > 1, correct? ``` select count(*) from my_table t group by t.a, t.b, t.c ``` Is there a better/alternative way to make this determination?

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