Adding an index column to an existing table in postrges sql

Question

I have a table with data that has no unique data anywhere on the table. I want to create a column that would serve as a unique identifier.

How do I add a new primary key column to the existing table?

Index and primary key syntax is readily available on Google and other Stack Overflow posts. A primary key is a unique value in the table. If you don't have a unique ID on the table anywhere, you can't use a primary key. — dfundako, Mar 14 '18 at 17:08
https://stackoverflow.com/questions/787722/postgresql-autoincrement — Jacob H, Mar 14 '18 at 17:14
That is precisely my question. How do I create a column that can be used as a primary key? — JoeJam, Mar 15 '18 at 13:54

score 0 · Accepted Answer · edited Apr 04 '18 at 17:49

0

You can use the following SQL statement to create a unique identifier (Primiry Key) in to your existing table.

ALTER TABLE your_table ADD  key_column SERIAL;

edited Apr 04 '18 at 17:49

JoeJam

answered Mar 14 '18 at 17:21

Zulfiqar Ali

This is invalid for Postgres – Mar 14 '18 at 17:33
One can also try this. ALTER TABLE your_table ADD COLUMN key_column BIGSERIAL PRIMARY KEY; – Zulfiqar Ali Mar 14 '18 at 17:38
I am using postrges for this project. – JoeJam Mar 15 '18 at 13:23
I ran the code you suggested and received the following error, "Cannot add column with primary key constraint". – JoeJam Mar 15 '18 at 13:59

1 Answers1