How do I avoid syntax error in FOR loops in postgresql? - postgresql

Question

I'm using PostgreSQL 10.5 and I have the following SQL:
FOR temprow IN
SELECT o.objectid, o.nametag, cor.userseqno, cor.commseqno
FROM "commuserobjectrights" as cor
LEFT JOIN "object" as o ON cor.objectid = o.objectid
WHERE o.nametag LIKE 'commission.video_questions'
LOOP
INSERT INTO u commuserobjectrights (objectid, commseqno, userseqno, access)
VALUES (temprow.objectid, temprow.commseqno, temprow.userseqno, TRUE);
END LOOP;
which throws the following error:
ERROR: syntax error at or near "FOR" Position: 3
I have never used loops before but according the documentation, postgresql should have support for these types of loops. And yes, I have checked and double checked that all tables and column names are spelled correctly.

Answer 1

You can't use FOR loops outside of procedural code. But, in general Postgres (and SQL) is optimized to already do set based operations. So, you may phrase this as an INSERT INTO ... SELECT:
INSERT INTO commuserobjectrights (objectid, commseqno, userseqno, access)
SELECT o.objectid, o.nametag, cor.userseqno, TRUE
FROM "commuserobjectrights" as cor
LEFT JOIN "object" as o ON cor.objectid = o.objectid
WHERE o.nametag LIKE 'commission.video_questions';

Answer 2

FOR is procedural code, so you need to use DO or use it in stored code.
DO $$
DECLARE
temprow record ;
BEGIN
FOR temprow IN
SELECT o.objectid, o.nametag, cor.userseqno, cor.commseqno
FROM "commuserobjectrights" as cor
LEFT JOIN "object" as o ON cor.objectid = o.objectid
WHERE o.nametag LIKE 'commission.video_questions'
LOOP
INSERT INTO commuserobjectrights (objectid, commseqno, userseqno, access)
VALUES (temprow.objectid, temprow.commseqno, temprow.userseqno, TRUE);
END LOOP;
END;
$$;
This is not the most efficient way to do this task but for other tasks where you can't easily write SQL DO may be useful.