How to update the data if it already exists and add it if it doesn't exist?

Question

PostgreSQL

For example, look. There is a table with fields id and chtoto (array) and you need to check if it has a record with id 74291910, for example, and if so, then update the record, if not, add a record. Here is the request I got:

INSERT INTO table (id, chtoto) VALUES (74291910, array_append(chtoto, 'string') 
ON CONFLICT (id) DO UPDATE SET chtoto=array_append(chtoto, 'string')

But there is a problem with this - chtoto is specified many times. How it is possible to rewrite this request correctly?

Answer 1

INSERT INTO table (id, chtoto) VALUES (74291910, array_append(chtoto, 'string') 
ON CONFLICT (id) DO UPDATE SET chtoto=EXCLUDED.chtoto

Answer 2

first insert with a unique field - the record will not be added if it already exists.
and then the update request.
More precisely, it is better to change places, probably. at first to update records that already are, and then to add. there will be no duplicates since id is made as a unique field.