Unfortunately Postgresql does not have Auto Increment columns so instead we create a Sequence that will act as a counter
First we’ll need to create a sequence that we want to attch to our table
CREATE SEQUENCE mytable_primary_id_seq;
Then we need to assign the sequence to the column in our table that will act as the Autoincrement column
ALTER TABLE mytable ALTER COLUMN primary_id SET DEFAULT NEXTVAL('mytable_primary_id_seq');
No we need to fill in an auto increment value for all records that existed in the tablebefore we added a sequence to the table column primary_id
UPDATE mytable SET primary_id = NEXTVAL('mytable_primary_id_seq');
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