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From:Andre Polykanine Date:February 15 2011 12:14am
Subject:Re: Insert only if the entry doesn't exist
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Hello Rolando,

So if I do
"INSERT IGNORE INTO `Votes` SET `EntryId`='12345', UserId`='789'";
it  *won't* insert the second row if there's a row with EntryId set to
12345 and UserId set to 789?
Thanks and sorry!)

-- 
With best regards from Ukraine,
Andre
Skype: Francophile
My blog: http://oire.org/menelion (mostly in Russian)
Twitter: http://twitter.com/m_elensule
Facebook: http://facebook.com/menelion

------------ Original message ------------
From: Rolando Edwards <redwards@stripped>
To: Andre Polykanine
Date created: , 11:01:40 PM
Subject: Insert only if the entry doesn't exist


      If the table has Primary and/or UNIQUE Keys, then you are fine.

You do not need to know what they are. If you want to see them do this:
SHOW CREATE TABLE Votes\G

INSERT IGNORE INTO does not require ON DUPLICATE KEY options.
After all, you said earlier that you want to do nothing if the row exists.

Rolando A. Edwards
MySQL DBA (SCMDBA)

155 Avenue of the Americas, Fifth Floor
New York, NY 10013
212-625-5307 (Work)
201-660-3221 (Cell)
AIM & Skype : RolandoLogicWorx
redwards@stripped
http://www.linkedin.com/in/rolandoedwards


-----Original Message-----
From: Andre Polykanine [mailto:andre@stripped] 
Sent: Monday, February 14, 2011 3:40 PM
To: Rolando Edwards
Cc: João Cândido de Souza Neto; mysql@stripped
Subject: Re: Insert only if the entry doesn't exist

Hello Rolando,

Sorry,  but  if  I  do  INSERT IGNORE INTO, then I must indicate a key
(typically a unique key or a primary key), or is it false? But I don't
know that key and no way to get it without more queries...

-- 
With best regards from Ukraine,
Andre
Skype: Francophile
My blog: http://oire.org/menelion (mostly in Russian)
Twitter: http://twitter.com/m_elensule
Facebook: http://facebook.com/menelion

------------ Original message ------------
From: Rolando Edwards <redwards@stripped>
To: João Cândido de Souza Neto
Date created: , 10:33:05 PM
Subject: Insert only if the entry doesn't exist


      Be Careful. REPLACE INTO mechanically does DELETE and INSERT under mysqld's hood.
If you want to do nothing if row exists already then do:

INSERT IGNORE instead of REPLACE INTO

Rolando A. Edwards
MySQL DBA (SCMDBA)

155 Avenue of the Americas, Fifth Floor
New York, NY 10013
212-625-5307 (Work)
201-660-3221 (Cell)
AIM & Skype : RolandoLogicWorx
redwards@stripped
http://www.linkedin.com/in/rolandoedwards


-----Original Message-----
From: João Cândido de Souza Neto [mailto:joao@stripped] 
Sent: Monday, February 14, 2011 1:39 PM
To: mysql@stripped
Subject: Re: Insert only if the entry doesn't exist

Instead of "insert into" you can use "replace into".

-- 
João Cândido de Souza Neto

"Andre Polykanine" <andre@stripped> escreveu na mensagem 
news:1621362474.20110214201216@ style="color:#666">stripped...
Hi all,
Thanks for your fast answer to my last question!
Here's one more problem I commonly deal with.
There  are  cases  when  I need to insert the row only if such a row
doesn't  exist,  otherwise  I  need either to update the row or to do
nothing, just skip the query.
The  common case is the rating increment/decrement. I have the + and -
links  which are AJAX. So I need to prevent fast multiple clicking and
over-increasing or over-decreasing the rating of the blog entry.
Here's what I'm doing, in a simplified form (assume all of the numbers
are PHP variables):
"SELECT `Id` FROM `Votes` WHERE `EntryId`='12345' AND `UserId`='789'";
then I'm checking if the user has already clicked a link:
if (mysql_num_rows()==0) {
"INSERT INTO `Votes` SET `EntryId`='12345', `UserId`='789'";
} else {
// do nothing
}

And here is the question (at last!):
How  can  I  MySql'ly  check whether a vote does exist and if it does,
then insert the row, else either do nothing or update several columns?
I  assume I can't use ON DUPLICATE KEY UPDATE because I have no unique
keys...
Hope you understood my problem).
Thanks!



-- 
With best regards from Ukraine,
Andre
Skype: Francophile
Twitter: http://twitter.com/m_elensule
Facebook: http://facebook.com/menelion



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Thread
Insert only if the entry doesn't existAndre Polykanine14 Feb
  • Re: Insert only if the entry doesn't existjoao14 Feb
    • RE: Insert only if the entry doesn't existRolando Edwards14 Feb
      • Re: Insert only if the entry doesn't existAndre Polykanine14 Feb
        • RE: Insert only if the entry doesn't existRolando Edwards14 Feb
          • Re: Insert only if the entry doesn't existAndre Polykanine15 Feb
            • Re: Insert only if the entry doesn't existJoerg Bruehe15 Feb