CODEWITHSUNDEEP
sql-serveroracle-databasesql-server-2008
user1141584
user1141584

Reputation: 619

Primary key detection

I have imported the data into an database.

Patient(pt_id,pt_name,pt_type,pt_loc)

Now , I want to find which of these a primary (have unique) values.

Any way I could found is 

     select count(pt_id) from patient
     select count(distinct pt_id) from patient

would return the same value

Any input would be great :)

Thanks!!!

Upvotes: 0

Views: 111

Answers (1)

Stuart Ainsworth
Stuart Ainsworth

Reputation: 12940

A single-pass method of determining if the column contains only unique values would be:

SELECT pt_id, COUNT(pt_id) from patient
GROUP BY pt_id
HAVING COUNT(pt_id) > 1

if you get results, it's not unique. You may also want to check for nulls:

SELECT * from patient
WHERE pt_id is NULL

Upvotes: 4

Related Questions