Insert only if the entry doesn"t exist
Insert only if the entry doesn"t exist
am 14.02.2011 19:12:16 von Andre Polykanine
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`=3D'12345' AND `UserId`=3D'789'";
then I'm checking if the user has already clicked a link:
if (mysql_num_rows()==0) {
"INSERT INTO `Votes` SET `EntryId`=3D'12345', `UserId`=3D'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!
--=20
With best regards from Ukraine,
Andre
Skype: Francophile
Twitter: http://twitter.com/m_elensule
Facebook: http://facebook.com/menelion
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Re: Insert only if the entry doesn"t exist
am 14.02.2011 19:38:40 von joao
Instead of "insert into" you can use "replace into".
--
João Cândido de Souza Neto
"Andre Polykanine" escreveu na mensagem
news:1621362474.20110214201216@oire.org...
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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RE: Insert only if the entry doesn"t exist
am 14.02.2011 21:33:05 von Rolando Edwards
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@logicworks.net
http://www.linkedin.com/in/rolandoedwards
-----Original Message-----
From: Jo=E3o C=E2ndido de Souza Neto [mailto:joao@consultorweb.cnt.br]=20
Sent: Monday, February 14, 2011 1:39 PM
To: mysql@lists.mysql.com
Subject: Re: Insert only if the entry doesn't exist
Instead of "insert into" you can use "replace into".
--=20
Jo=E3o C=E2ndido de Souza Neto
"Andre Polykanine" escreveu na mensagem=20
news:1621362474.20110214201216@oire.org...
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`=3D'12345' AND `UserId`=3D'789'";
then I'm checking if the user has already clicked a link:
if (mysql_num_rows()==0) {
"INSERT INTO `Votes` SET `EntryId`=3D'12345', `UserId`=3D'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!
--=20
With best regards from Ukraine,
Andre
Skype: Francophile
Twitter: http://twitter.com/m_elensule
Facebook: http://facebook.com/menelion
--=20
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe: http://lists.mysql.com/mysql?unsub=3Dredwards@logicworks=
..net
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Re: Insert only if the entry doesn"t exist
am 14.02.2011 21:39:38 von Andre Polykanine
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...
--=20
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
To: Jo=E3o C=E2ndido 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 my=
sqld'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@logicworks.net
http://www.linkedin.com/in/rolandoedwards
-----Original Message-----
From: Jo=E3o C=E2ndido de Souza Neto [mailto:joao@consultorweb.cnt.br]=20
Sent: Monday, February 14, 2011 1:39 PM
To: mysql@lists.mysql.com
Subject: Re: Insert only if the entry doesn't exist
Instead of "insert into" you can use "replace into".
--=20
Jo=E3o C=E2ndido de Souza Neto
"Andre Polykanine" escreveu na mensagem=20
news:1621362474.20110214201216@oire.org...
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`=3D'12345' AND `UserId`=3D'789'";
then I'm checking if the user has already clicked a link:
if (mysql_num_rows()==0) {
"INSERT INTO `Votes` SET `EntryId`=3D'12345', `UserId`=3D'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!
--=20
With best regards from Ukraine,
Andre
Skype: Francophile
Twitter: http://twitter.com/m_elensule
Facebook: http://facebook.com/menelion
--=20
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe: http://lists.mysql.com/mysql?unsub=3Dredwards@logicworks=
..net
--=20
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RE: Insert only if the entry doesn"t exist
am 14.02.2011 22:01:40 von Rolando Edwards
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@logicworks.net
http://www.linkedin.com/in/rolandoedwards
-----Original Message-----
From: Andre Polykanine [mailto:andre@oire.org]=20
Sent: Monday, February 14, 2011 3:40 PM
To: Rolando Edwards
Cc: Jo=E3o C=E2ndido de Souza Neto; mysql@lists.mysql.com
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...
--=20
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
To: Jo=E3o C=E2ndido 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 my=
sqld'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@logicworks.net
http://www.linkedin.com/in/rolandoedwards
-----Original Message-----
From: Jo=E3o C=E2ndido de Souza Neto [mailto:joao@consultorweb.cnt.br]=20
Sent: Monday, February 14, 2011 1:39 PM
To: mysql@lists.mysql.com
Subject: Re: Insert only if the entry doesn't exist
Instead of "insert into" you can use "replace into".
--=20
Jo=E3o C=E2ndido de Souza Neto
"Andre Polykanine" escreveu na mensagem=20
news:1621362474.20110214201216@oire.org...
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`=3D'12345' AND `UserId`=3D'789'";
then I'm checking if the user has already clicked a link:
if (mysql_num_rows()==0) {
"INSERT INTO `Votes` SET `EntryId`=3D'12345', `UserId`=3D'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!
--=20
With best regards from Ukraine,
Andre
Skype: Francophile
Twitter: http://twitter.com/m_elensule
Facebook: http://facebook.com/menelion
--=20
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe: http://lists.mysql.com/mysql?unsub=3Dredwards@logicworks=
..net
--=20
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For list archives: http://lists.mysql.com/mysql
To unsubscribe: http://lists.mysql.com/mysql?unsub=3Dandre@oire.org
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Re: Insert only if the entry doesn"t exist
am 15.02.2011 01:14:57 von Andre Polykanine
Hello Rolando,
So if I do
"INSERT IGNORE INTO `Votes` SET `EntryId`=3D'12345', UserId`=3D'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!)
--=20
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
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@logicworks.net
http://www.linkedin.com/in/rolandoedwards
-----Original Message-----
From: Andre Polykanine [mailto:andre@oire.org]=20
Sent: Monday, February 14, 2011 3:40 PM
To: Rolando Edwards
Cc: Jo=E3o C=E2ndido de Souza Neto; mysql@lists.mysql.com
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...
--=20
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
To: Jo=E3o C=E2ndido 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 my=
sqld'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@logicworks.net
http://www.linkedin.com/in/rolandoedwards
-----Original Message-----
From: Jo=E3o C=E2ndido de Souza Neto [mailto:joao@consultorweb.cnt.br]=20
Sent: Monday, February 14, 2011 1:39 PM
To: mysql@lists.mysql.com
Subject: Re: Insert only if the entry doesn't exist
Instead of "insert into" you can use "replace into".
--=20
Jo=E3o C=E2ndido de Souza Neto
"Andre Polykanine" escreveu na mensagem=20
news:1621362474.20110214201216@oire.org...
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`=3D'12345' AND `UserId`=3D'789'";
then I'm checking if the user has already clicked a link:
if (mysql_num_rows()==0) {
"INSERT INTO `Votes` SET `EntryId`=3D'12345', `UserId`=3D'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!
--=20
With best regards from Ukraine,
Andre
Skype: Francophile
Twitter: http://twitter.com/m_elensule
Facebook: http://facebook.com/menelion
--=20
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe: http://lists.mysql.com/mysql?unsub=3Dredwards@logicworks=
..net
--=20
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Re: Insert only if the entry doesn"t exist
am 15.02.2011 19:58:40 von Joerg Bruehe
Hi!
Andre Polykanine wrote:
> Hello Rolando,
>=20
> So if I do
> "INSERT IGNORE INTO `Votes` SET `EntryId`=3D'12345', UserId`=3D'789'";
> it *won't* insert the second row if there's a row with EntryId set to
> 12345 and UserId set to 789?
If you want to have at most one vote per user on any entry, IMO you
should have a "unique index" on that combination of fields.
Aside:
Assuming you "*Id" values are numeric types, you should stop using
quotes around them: quotes enclose strings.
I know MySQL implicitly converts numbers to strings and vice versa, but
this costs performance and IMO is a bad idea anyways.
I feel a programmer should know the distinction of numeric and string
types and keep them separate in a well-structured application.
HTH,
Jörg
--=20
Joerg Bruehe, MySQL Build Team, joerg.bruehe@oracle.com
ORACLE Deutschland B.V. & Co. KG, Komturstrasse 18a, D-12099 Berlin
Geschaeftsfuehrer: Juergen Kunz, Marcel v.d. Molen, Alexander v.d. Ven
Amtsgericht Muenchen: HRA 95603
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