Update table based on self table lookup in redshift

Question

I have the below table,

id   email   mgr_email   mgr_id
-------------------------------
1    email1   email2    
2    email2   email3
3    email3   email4


        

Answer 1

Use sub query for self join:

Try this:

update mytable 
    set mgr_id=t2.id 
    from (select id, email from mytable) t2 
    where mytable.mgr_email=t2.email

Answer 2

It's a bit ugly but you really have to write the subquery with self-join and only then update the table from it:

update mytable
set mgr_id=t.id
from (
    select t1.email,t2.id
    from mytable t1 
    join mytable t2
    on t1.mgr_email=t2.email
) t
where mytable.email=t1.email;

as said in comments, it's the particular case of more generic update from table syntax