sql-delete

Say we have a PostgreSQL table like so: CREATE TABLE master ( id INT PRIMARY KEY, ... ); and many other tables referencing it with foreign keys: CREATE TABLE other ( id INT PRIMARY KEY, id_master INT NOT NULL, ... CONSTRAINT other_id_master_fkey FOREIGN KEY (id_master) REFERENCES master (id) ON DELETE RESTRICT ); Is there a way to check (from within trigger function) if a master row is deletable without actually trying to delete it? The obvious way is to do a SELECT on all referencing tables one by one, but I would like to know if there is an easier way. The reason I need this is that I have a

I have a PHP script that runs a SELECT query then immediately deletes the record. There are multiple machines that are pinging the same php file and fetching data from the same table. Each remote machine is running on a cron job. My problem is that sometimes it is unable to delete fast enough since some of the machines ping at the exact same time. My question is, how can I SELECT a record from a database and have it deleted before the next machine grabs it. For right now I just added a short delay but it's not working very well. I tried using a transaction, but I don't think it applies here.

I'm new to Python and Python's MySQL adapter. I'm not sure if I'm missing something obvious here: db = MySQLdb.connect(# db details omitted) cursor = self.db.cursor() # WORKS cursor.execute("SELECT site_id FROM users WHERE username=%s", (username)) record = cursor.fetchone() # DOES NOT SEEM TO WORK cursor.execute("DELETE FROM users WHERE username=%s", (username)) Any ideas? Bill Karwin I'd guess that you are using a storage engine that supports transactions (e.g. InnoDB) but you don't call db.commit() after the DELETE. The effect of the DELETE is discarded if you don't commit. See http://mysql

I am new to SQL. We have some code that should work on SQL Server 2005/2008, Oracle 10 as well as Sybase. I was writing a script to try to figure out which tables a given stored procedure modifies (but does not drop), e.g insert , update and delete . The delete one turned out being puzzling - sometimes I see statements like: delete phone_book where ... as opposed to: delete from phone_book where ... So ... is the from keyword truly optional in this case? Does this cause any problems? Is it just a bad style, or does it not matter? I have not found a reference to T-SQL that would make from

I am having a very hard time solving my problem with the multiple checkbox delete. Can someone direct me to the solution? What is supposed to happen here is that the user can tick the boxes and click a delete button to delete the ticked ones. Unfortunately, my code doesn't seem to work; can you point me in the right direction? <div id="container" class="page"> <img id="disclaimer" class="page" src="images/DISCLAIMER.png" alt="" /> <img id="logo" class="page" src="images/MI-LOGO.png" alt="" /> <div id="videoContainer" class="page"> <video id="video" controls> <source src="video/animationTest