PostgreSQL multi-table query with name, first_name, and last_name

Question

I have two tables in my PostgreSQL database.

One table, call it 'Archive', has a column 'name' which are two-word first-name and last-name, eg 'John Smith' and an empty column which wants to be full of 'user_id'.

The second table, call it 'User Accounts', has three columns, one 'first_name' and one 'last_name' and one 'id'.

My goal is to implement a query that uses the column in Archive to select for the corresponding first_name and last_name in User Accounts and return to Archive the 'id' into 'user_id' column

Answer 1

You can use a join . For instance:

select a.*, ua.id as user_id
from archive a left join
     user_accounts ua
     on a.name = ua.first_name || ' ' || ua.last_name;

If you actually want to update the column:

update archive a 
    set user_id = ua.id
    from user_accounts ua
    where a.name = ua.first_name || ' ' || ua.last_name;

Note that name matching can be quite tricky. You may not get as many matches as you expect. If this turns out to be an issue, ask another question . Include sample data and desired results in the question.