如何从pgsql中的列表中选择数据

Question

In PostgreSQL I am able to pick data from the query of a table. As for example I want to display entityname from t1 using for loop.

DO
$do$
DECLARE
   e varchar;
BEGIN
   FOR e IN (SELECT entityname 
              FROM t1)
  LOOP

 raise notice 'Value: %', e;

END LOOP;
END
$do$;

But If I already have list of entityname and I just want to display it. What will be the correct way, I tried using

DO
$do$
DECLARE
   e varchar;
BEGIN
  FOR e IN ('t1','t2')
  LOOP

 raise notice 'Value: %', e;

END LOOP;
END
$do$;

But it is giving error

ERROR:  syntax error at or near "'t1'"
LINE 6:   FOR e IN ('t1','t2')

What will be the right way to do this ?

Answer 1

The correct statement is FOREACH target IN ARRAY , which iterates over a array:

FOREACH target [ SLICE number ] IN ARRAY expression LOOP
    statements
END LOOP;

Also in you case:

DO $do$ DECLARE e varchar;
BEGIN
  FOREACH e IN ARRAY ARRAY['t1','t2'] LOOP    
    raise notice 'Value: %', e;    
  END LOOP;
END $do$;