How to do a Postgresql subquery in select clause with join in from clause like SQL Server?

Question

I am trying to write the following query on postgresql:

select name, author_id, count(1), 
    (select count(1)
    from names as n2
    where n2.id = n1.id
             


        

Answer 1

I know this is old, but since Postgresql 9.3 there is an option to use a keyword "LATERAL" to use RELATED subqueries inside of JOINS, so the query from the question would look like:

SELECT 
    name, author_id, count(*), t.total
FROM
    names as n1
    INNER JOIN LATERAL (
        SELECT 
            count(*) as total
        FROM 
            names as n2
        WHERE 
            n2.id = n1.id
            AND n2.author_id = n1.author_id
    ) as t ON 1=1
GROUP BY 
    n1.name, n1.author_id