So I'm trying to write an sql query to be execute from php to count number of downloads of a files. I have a table id,name,count and I want it to check if the name exists and increment count else to insert a new row.
I was trying to use if exists but that didn't work so now I'm trying to use the on duplicate key update statement. I inserted a row with the name lemons as a test case. I keep getting the error with my syntax near the WHERE statement. Am I approaching this right?
INSERT INTO `table` (`name`, `count`)
VALUES ('lemons',1) ON DUPLICATE KEY
UPDATE `count` = `count`+1
WHERE `name` = 'lemons';
Related
My goal is to only execute a SQL Insert if the same value not exists.
this is my table1:
id(auto_increment)
version(string)
My Query looks like this:
INSERT IGNORE INTO table1 (version) VALUES ('12345');
The problem is that the ignore statement not work because every row is different because of the id column (auto_increment).
Anybody here have a Solution to avoid double saving the same values?
Solution:
INSERT INTO table1 (version)
SELECT * FROM (SELECT '12345') AS tmp
WHERE NOT EXISTS (
SELECT version FROM table1 WHERE version = '12345'
) LIMIT 1;
Your issue has nothing to do with the auto-incremented column.
You need a unique constraint/index on version:
alter table table1 constraint unq_table1_version unique (version);
I also don't recommend insert ignore for this purpose. It might ignore other errors. Instead, use on duplicate key update:
insert into table1 (version)
values ('12345')
on duplicate key update version = values(version); -- this is a no-op
I have the following database MySQL table.
id (PK, AI)
email
country
lastlogin
I have a regular query in PHP that inserts this into the table.
however, logically, if this code runs several times, the same row will be inserted to the database every time.
I want my reference for checking and duplication to be the email field, and if the email is the same, update the country and the lastlogin.
I checked on other questions for a similar issue and the suggested way was to use ON DUPLICATE KEY like this
INSERT INTO <table> (field1, field2, field3, ...)
VALUES ('value1', 'value2','value3', ...)
ON DUPLICATE KEY UPDATE
field1='value1', field2='value2', field3='value3', ...
However, my primary key is not the email field rather the id but I don't want to run the check on it.
One option is make the email field unique, and then it should behave the same as primary key, at least with regard to MySQL's ON DUPLICATE KEY UPDATE:
ALTER TABLE yourTable ADD UNIQUE INDEX `idx_email` (`email`);
and then:
INSERT INTO yourTable (email, country, lastlogin)
VALUES ('tony9099#stackoverflow.com', 'value2', 'value3')
ON DUPLICATE KEY UPDATE
email='value1', country='value2', lastlogin='value3'
If the email tony9099#stackoverflow.com already exists in your table, then the update would kick in with alternative values.
From the MySQL documentation:
If you specify ON DUPLICATE KEY UPDATE, and a row is inserted that would cause a duplicate value in a UNIQUE index or PRIMARY KEY, MySQL performs an UPDATE of the old row.
This approach doesn't only work with primary keys, it also works with any column having a unique index.
As Dan has mentioned, the ROW_COUNT() in-built function does not support this solution with a standard configuration.
MySQL::ROW_COUNT()
For UPDATE statements, the affected-rows value by default is the number of rows actually changed. If you specify the CLIENT_FOUND_ROWS flag to mysql_real_connect() when connecting to mysqld, the affected-rows value is the number of rows “found”; that is, matched by the WHERE clause.
If modifying the database schema is not an option, you could use the following method:
UPDATE `table` SET `country`='value1', `lastlogin`='value1' WHERE `email`='value3'
IF ROW_COUNT()=0
INSERT INTO `table` (`email`, `country`, `lastlogin`) VALUES ('value1', 'value2', 'value3')
you can use
$query=mysql_query("select * from table where email = 'your email'");
if(mysql_num_rows($query) > 0){
//update
}else{
//insert
}
You can load a row with the given email first and then decide if you have to insert or update depending on the existence of the loaded row. This needs multiple SQL statements, but it can be written in a DBMS vendor independent way. Use a surrounding transaction to handle concurrency. An index on the email-column is useful to keep the existence - check fast. Adding a unique - constraint on the email-column is an option to guarantee that there will never be multiple rows with same email.
You can do it manually like before inserting the value to table first check whether the value exists in table or not if yes then update your related field
$qry = mysql_query("select * from table where email='abc#abc.com'");
$count = mysql_num_rows($qry);
if($count > 0){
write your update query here
}else{
write your insert query here
}
Here is what I want to do. Insert if the unique index (code) doesn't exist in the table already. If it exists then simply update the row.
I can't use primary key because it is Auto Increment ID. Here is the code
$sql="INSERT INTO codes (code,registration,country)
VALUES ('$war','$regi','$country') ON DUPLICATE KEY UPDATE code='$war', registration='$regi', country='$country'";
But it doesn't work because I think it is checking for duplicate primary key. So when I try to insert the row in which the value of column code is same as previous row I get Duplicate entry 'xxx' for key 'code' error. So how to make this work for unique index code ?
Ahmar
ON DUPLICATE KEY UPDATE works with UNIQUE indexes as well as PRIMARY KEY values. Try setting one of the values you are trying to update to be UNIQUE on your database table.
All you have to do is set code to be a unique index. Then, anytime you try to do an insert where code matches it will update instead.
Alter this code as needed
alter table `table` add unique index(`code`);
You are correct, having a primary key on your table will not allow you to insert duplicate key values.
In the past, I have used something like this:
SELECT COUNT(*)
FROM codes
WHERE code = '$war'
Then if the count is > 0, you know there's a duplicate and you do:
UPDATE codes
SET registration = '$regi', country = '$country'
WHERE code = '$war'
Otherwise you do:
INSERT INTO codes (code, registration, country)
VALUES ('$war', '$regi', '$country')
However, if we assume you're using MySQL, you might be able to make use of either INSERT IGNORE or REPLACE.
If you use:
INSERT IGNORE codes (code, registration, country)
VALUES ('$war', '$regi', '$country')
The values will be inserted if the code does not already exist. If the code does exist, no record is inserted and MySQL will silently discard the statement without generating an error.
I think what you probably want is this:
REPLACE INTO codes (code, registration, country)
VALUES ('$war', '$regi', '$country')
REPLACE INTO behaves just like INSERT INTO if the record is new. But if the primary key is duplicated, it will perform an UPDATE instead.
Again, INSERT IGNORE and REPLACE INTO are for MySQL only.
Reference: http://www.tutorialspoint.com/mysql/mysql-handling-duplicates.htm
I have a following
Table1 : userid, who, share, date :: id is auto increment and primary key
I would like to build a query to check if record exist and insert new record if is empty.
How to build this in a single query and insert multiple records using a single query
data to inser ('a1','a2','a3','a4'), ('b1','b2','b3','b4'), ('c1','c2','c3','c4'), .......
Create UNIQUE index on column that you want to be unique
Use INSERT IGNORE to insert unique data and ignore not unique
You could use REPLACE statemement that works just like INSERT only it doesn't do anything if the row already exists:
REPLACE INTO table ...
http://dev.mysql.com/doc/refman/5.0/en/replace.html
You should take careful look at mysql INSERT INTO documentation.
How to insert "on no exists" is simple. Let's say you want combination of user,who,share to be unique and use latest date. Update your table and create UNIQUE KEY on those fields:
ALTER TABLE Table1 ADD UNIQUE KEY (user, who, share);
Normally inserting the same combination would cause error but using INSERT IGNORE (link above) would silently ignore error:
INSERT IGNORE INTO Table1 (user,who,share,date) VALUES ( 1, 2, 3, NOW());
You may also force key to update on insert:
INSERT IGNORE INTO Table1 (user,who,share,date) VALUES ( 1, 2, 3, NOW())
ON DUPLICATE KEY UPDATE date = VALUES(date);
And inserting multiple values at once, again the first link:
INSERT INTO tbl_name (a,b,c) VALUES(1,2,3),(4,5,6),(7,8,9);
This question already has answers here:
MySQL 'UPDATE ON DUPLICATE KEY' without a unique column?
(3 answers)
Closed 10 months ago.
I'm trying to create more robust MySQL Queries and learn in the process. Currently I'm having a hard time trying to grasp the ON DUPLICATE KEY syntax and possible uses.
I have an INSERT Query that I want to INSERT only if there is no record with the same ID and name, otherwise UPDATE. ID and name are not UNIQUE but ID is indexed.ID isn't UNIQUE because it references another record from another table and I want to have multiple records in this table that reference that one specific record from the other table.
How can I use ON DUPLICATE KEY to INSERT only if there is no record with that ID and name already set else UPDATE that record?
I can easily achieve this with a couple of QUERIES and then have PHP do the IF ELSE part, but I want to know how to LIMIT the amount of QUERIES I send to MySQL.
UPDATE: Note you need to use IF EXISTS instead of IS NULL as indicated in the original answer.
Code to create stored procedure to encapsulate all logic and check if Flavours exist:
DELIMITER //
DROP PROCEDURE `GetFlavour`//
CREATE PROCEDURE `GetFlavour`(`FlavourID` INT, `FlavourName` VARCHAR(20))
BEGIN
IF EXISTS (SELECT * FROM Flavours WHERE ID = FlavourID) THEN
UPDATE Flavours SET ID = FlavourID;
ELSE
INSERT INTO Flavours (ID, Name) VALUES (FlavourID, FlavourName);
END IF;
END //
DELIMITER ;
ORIGINAL:
You could use this code. It will check for the existence of a particular record, and if the recordset is NULL, then it will go through and insert the new record for you.
IF (SELECT * FROM `TableName` WHERE `ID` = 2342 AND `Name` = 'abc') IS NULL THEN
INSERT INTO `TableName` (`ID`, `Name`) VALUES ('2342', 'abc');
ELSE UPDATE `TableName` SET `Name` = 'xyz' WHERE `ID` = '2342';
END IF;
I'm a little rusty on my MySQL syntax, but that code should at least get you most of the way there, rather than using ON DUPLICATE KEY.
id and name are not unique but id is
indexed. id isn't unique
How can I use ON DUPLICATE KEY to
INSERT only if there is no record with
that id and name already set else
UPDATE that record?
You can't. ON DUPLICATE KEY UPDATE needs a unique or primary key to determine which row to update. You are better off having PHP do the IF ELSE part.
edit:
If the combination of name and id IS supposed to be unique, you can create a multi-column UNIQUE index. From there you can use ON DUPLICATE KEY UPDATE.
Why not just use a stored procedure, then you can embed all the logic there are plus you have a reusable piece of code (e.g. the stored proc) that you can use in other applications. Finally, this only requires one round trip to the server to call the stored proc.