I'm developing a php script in which I insert multiple data into a mysql table, but some of this data may already be inserted. I can try to insert each of the individual data and detect the #1062 error (duplicate entry), but it would be very inefficient since it can be more than 100 entries. So, is there any way to do this in one query or must I use a query for each entry to be inserted?
Thanks a lot.
You'll want to use the INSERT ... ON DUPLICATE KEY UPDATE command to accomplish this. In the "ON DUPLICATE KEY UPDATE" section, you can just do some kind of update that changes nothing. For example, "SET fieldName=fieldName", just so nothing is actually changed.
http://dev.mysql.com/doc/refman/5.0/en/insert-on-duplicate.html
Related
I have an app that has to import TONS of data from a remote source. From 500 to 1500 entries per call.
Sometimes some of the data coming in will need to replace data already stored in the dB. If I had to guess, I would say once in 300 or 400 entries would one need to be replaced.
Each incoming entry has a unique ID. So I am trying to figure out if it is more efficient to always issue a delete command based on this ID or to check if there is already an entry THEN delete.
I found this SO post where it talks about the heavy work a dB has to do to delete something. But it is discussing a different issue so I'm not sure if it applies here.
Each incoming entry has a unique ID. So I am trying to figure out if it is more efficient to always issue a delete command based on this ID or to check if there is already an entry THEN delete.
Neither. Use INSERT ... ON DUPLICATE KEY UPDATE ....
Since you are using MySQL and you have a unique key then let MySQL do the work.
You can use
INSERT INTO..... ON DUPLICATE KEY UPDATE......
MySQL will try to insert a new record in the table, is the unique value exists in the table then MySQL will update all the field that you have set after the update
You can read more about the INSERT INTO..... ON DUPLICATE KEY UPDATE...... syntax on
http://dev.mysql.com/doc/refman/5.0/en/insert-on-duplicate.html
I need to insert new row into table foo. But before insert those data, I need to check there was already inserted a row for the respective user name. If there has been already inserted, then I need to update the current data with the new data.
I know to do this using PHP if condition. But I love to do this using MySQL functions/statements by just a one line. Please can anyone help me?
For the example, kindly use the following statement. It should be updated.
$in = "insert into foo(username, text) values('user-x', 'user-x-text')";
Mysql_query($in);
When searching for similar questions, I got this post: Similar question with an answer. But I was struggle to use that solution since I don't know, the process occur by that code snippet will get down the server resources like speed etc. Because this script will run about 20 times per user.
Thank you.
I think INSERT ... ON DUPLICATE KEY UPDATE should be able to work
Make username a UNIQUE index, it doesn't have to be a primary key
If I'm not mistaken, DUPLICATE KEY will run only when you have a collision in any of the columns you supply that is either a primary key or unique index. In your case, text column is neither so it will be ignored for collisions.
INSERT... ON DUPLICATE KEY UPDATE works on unique indexes as confirmed by the MySql docs
In an application I'm building I use a lot of insert on duplicate key updates. My issue is that in my application I kind of need to know whether or not it was an insert or an update so my code can make the appropriate decisions. Does anyone know how I can test for this?
I'm using perl's DBI module if anyone knows a way specific to that. Thanks!
Per the documentation:
With ON DUPLICATE KEY UPDATE, the affected-rows value per row is 1 if
the row is inserted as a new row and 2 if an existing row is updated.
So, you should be able to check the return-value of the INSERT .. ON DUPLICATE KEY queries; if it's 1, the row was inserted, if it is 2, it was updated.
I'm trying to create a code for a single button where it will perform either of two actions where it will add to the database if the user currently don't have the record while it will update the user's record if the user has records already. I've done it like this:
if() {
mysql_query("INSERT INTO table...");
}
else {
mysql_query("UPDATE table SET...");
}
Is it possible?
Yes, what you've written will work. If you have a way to know if there already exists a row or not without making an additional query just for this bit of code, then do exactly as you wrote.
If, however, you planned to first SELECT from the table to see if a row exists, then conditionally INSERT or UPDATE, you will perform more queries than necessary.
It would be better to either:
Have a PRIMARY KEY or other constraint on the table prevent duplicate INSERTs. Then issue an INSERT ... ON DUPLICATE KEY UPDATE query. This will attempt to INSERT the row, and if it is a duplicate, automatically perform the specified UPDATE to that row instead.
Issue the UPDATE query and check mysql_affected_rows to see if it updated an existing row. If not, then issue the INSERT query to create the new row.
Which one is more appropriate depends on your application.
you can use INSERT ... ON DUPLICATE KEY UPDATE Syntax like:
INSERT INTO table (a,b,c) VALUES (1,2,3)
ON DUPLICATE KEY UPDATE c=c+1;
http://dev.mysql.com/doc/refman/5.0/en/insert-on-duplicate.html
If you have properly set unique keys, you should use REPLACE so you could remove the if.
REPLACE INTO table VALUE (...);
Pay attention that this is a MySQL extension, thus not portable to other DBs.
Yes, you could try the insert then if it fails try the update.
But you could use the MYSQL sql "REPLACE" keyword, which will insert a new record if it doesn't exist or delete the existing record and insert your new one if it does.
You could also use the INSERT ... ON DUPLICATE KEY UPDATE syntax
(explained here - Link to MYSQL ref which seems to be the closest fit to your requirement.
yes it is possible
first write a query for check that record is already exist or not.
Yes it is possible , it will work
I have two INSERT commands, that are useless to me like that because the two sets of rows - the ones that are already in the table, and the ones I have as INSERT commands - are not disjunct. Both commands insert lots of rows, and lots of values.
Therefore I get the duplicate entry error if I want to execute those lines.
Is there any easy way to 'convert' those commands into UPDATE?
I know this sounds stupid, because why do I make INSERT commands, if I want to UPDATE. Just to make it a clear scenario: another developer gave me the script:)
Thanks in advance,
Daniel
EDIT - problem solved
First I created a table and filled it up with my INSERT commands, then I used the following REPLACE command:
REPLACE
INTO table_1
SELECT *
FROM table_2;
This can originally be found at: How can I merge two MySQL tables?
MySQL's REPLACE keyword does this. Simply replace the INSERT keyword in your queries with the word REPLACE and it should update the rows instead of inserting new ones. Please note that it will only work if you're inserting a primary key or unique key column.
You would have to rewrite them to updates by hand. If I encouter such a problem, I query for the count of certain primary key first, if none is found I insert a generic dataset and update it afterwards. By this, new data can be added and already existing data will be updated, and you don't have to differentiate between inserting new data and updating data.
For MySQL, you can use either the INSERT IGNORE or the INSERT ... ON DUPLICATE UPDATE syntaxes. See the MySQL reference manual
You can easily modify your queries to update duplicate rows, see INSERT ... ON DUPLICATE KEY syntax in MySQL