PSQL - Copy from csv file if column item does not exist - postgresql

Question

I am trying to import a csv file into the postgres table where I can successfully do so using COPY FROM:
import.sql
\copy myTable FROM '..\CSV_OUTPUT.csv' DELIMITER ',' CSV HEADER;
But that query only adds rows if it is currently not in the database, otherwise it exits with an error. Key (id)=(#) already exists.
myTable
id | alias | address
------+-------------+---------------
11 | red_foo | 10.1.1.11
12 | blue_foo | 10.1.1.12
CSV_OUTPUT.csv
id | alias | address
------+-------------+---------------
10 | black_foo | 10.1.1.11
12 | blue_foo | 10.1.1.12
13 | grey_foo | 10.1.1.13
14 | pink_foo | 10.1.1.14
My desired output is to insert the rows from the csv file into postgresql if address does not exist. myTable should contain grey_foo and pink_foo already but not black_foo since its address already exist.
What should be the right queries to use in order to achieve this? Your suggestions and ideas are highly appreciated.

Answer 1

Copy the data into a staging table first, and then update your main table (myTable) with only the rows with the keys that don't already exist. For example, assuming you have imported the data into a table named staging:
with nw as (
select s.id, s.alias, s.address
from staging as s
left join mytable as m on m.address=s.address
where m.address is null
)
insert into mytable
(id, alias, address)
select id, alias, address
from nw;
If you can upgrade to Postgres 9.5, you could instead use an INSERT command with the ON CONFLICT DO NOTHING clause.