Select For Update statement in PostgreSql

Question

I want to select fields in a record of a table and update just one of these fields. How can I do?

I try this:

SELECT v.idvideo, v.title 
FROM video v  WHERE v.schedulingflag IS FALSE AND v.errorflag IS FALSE 
ORDER BY v.idvideo  LIMIT 1 FOR UPDATE ;

UPDATE video  SET schedulingflag = true;

But in this way it sets field "schedulingflag" true in all record!

Answer 1

The SELECT FOR UPDATE syntax tells PG that you're going to be updating those records and locks them against concurrent access. However you still need to issue the appropriate UPDATE call to change the particular records you've locked.

In this case, just use the same WHERE clause in your UPDATE, e.g:

UPDATE video  SET schedulingflag = true 
WHERE schedulingflag IS FALSE AND errorflag IS FALSE;