由于存在多个步骤，PSQL查询语法错误

Question

I'm running a simple update query that is hitting all sorts of syntax errors and I can't figure out why.

This select runs fine:

SELECT quote, author
FROM inspiration
WHERE length(quote)<250
AND used IS NULL
OR used > now()::date - 365
OFFSET floor(random()*10)
LIMIT 1;

While this get's a syntax error:

UPDATE inspiration SET used=now()
WHERE length(quote)<250
AND used IS NULL
OR used > now()::date - 365
OFFSET floor(random()*10)
LIMIT 1;

Removing OFFSET floor(random()*10) LIMIT 1 solves the issue. But I need one single random row updated.

Running EXPLAIN doesn't help since it's a syntax error. Wrapping both WHERE statements in parenthesis doesn't help.

Answer 1

But I need one single random row updated.

If I understand you correctly you want something like:

UPDATE inspiration
SET used = now()
WHERE id = (SELECT id          -- PK of inspiration table
            FROM inspiration
            WHERE length(quote)<250
              AND used IS NULL
                  OR used > now()::date - 365
            ORDER BY random() LIMIT 1);  

Also I belive that:

length(quote)<250
AND used IS NULL
OR used > now()::date - 365

-- should be
length(quote)<250
AND (used IS NULL
     OR used > now()::date - 365)