How to write SQL query with CASE?

Question

PostgreSQL

Good day.
How to write a query like this:

SELECT CASE WHEN a=0 THEN
          UPDATE table SET b=0
          my_function()
    WHEN a=1
          UPDATE table SET b=1
          my_function()
   ELSE my_function()
END;

On Mysql, this worked, although IF was used instead of CASE. And postgresql throws the error "syntax error (example position: 'table')"

Answer 1

don't forget about ;
but in your case you can't use update inside select. it's against the rules. Either write storage, or some other option.