I got a MySQL database with some tables.
In one of these tables i want to insert by a SQL script some new rows.
Unfortunately i have to insert in two columns an empty string and the two columns are part of an unique key for that table.
So i tried to set UNIQUE_CHECKS before and after the insert, but i'm getting errors because of duplicate entries.
Here is the definition of the table:
CREATE TABLE `Table_A` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(100) NOT NULL,
`number` varchar(25) DEFAULT NULL,
`changedBy` varchar(150) DEFAULT NULL,
`changeDate` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
PRIMARY KEY (`id`),
UNIQUE KEY `name` (`name`,`number`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
And the INSERT statement which causes error:
SET UNIQUE_CHECKS = 0;
INSERT INTO `Table_A`
(`name`, `number`, `changedBy`, `changeDate`)
SELECT DISTINCT '', 'myUser', CURRENT_TIMESTAMP
FROM Table_A
AND id NOT IN
(
SELECT DISTINCT id
FROM Table_A
);
SET UNIQUE_CHECKS = 1;
As You can see, i'm using UNIQUE_CHECKS.
But as i said this doesn't work properly.
Any help or suggestion would be appreciated.
Patrick
Switching off Unique Keys for the insert operation doesn't indicate that it will check uniqueness only for the operations that happen after you switch it on again. It just means that database will not waste time to check the constraint during the time it is switch off but it will check the constraint when you switch it on again.
What it measn is that you nead to ensure that column has unique value in a columns with Unique Keys before you can turn it on. Which you don't do.
If you want to maintain Uniqueness somehow for new records you insert after some point in time you would need to create trigger and manually check the new records against already existing data. The same possibly goes for updates. But I don't recommend it - you should probably redesign data so either the Unique Key is not there or the data is truly unique for all the records there are and will be.
Related
I'm trying to use on duplicate key update but it's not affecting any rows.
My table create statement, where you can see that I've created a unique key on childid and date.
CREATE TABLE `history_childfees` (
`childid` int(11) DEFAULT NULL,
`date` date DEFAULT NULL,
`amount` decimal(10,2) DEFAULT NULL,
`feetypecode` varchar(45) DEFAULT NULL,
UNIQUE KEY `key_childdate` (`childid`,`date`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
These are the two rows I have in the table.
The row I'm trying to update is the first row, by changing the amount for child 86615 on 2019-03-22.
insert into history_childfees (childid,date,amount,feetypecode)
values(86615,'2019-03-22',50,'DAY')
on duplicate key update childid = 86615, date = '2019-03-22';
I've also tried this syntax.
insert into history_childfees (childid,date,amount,feetypecode)
values (86615,'2019-03-22',50,'DAY')
on duplicate key update childid = values(childid), date = values(date);
Either way, it does not perform an insert and there's no error when I execute but it affects 0 rows. What am I missing here?
Consider:
CREATE TABLE `history_childfees` (
...
UNIQUE KEY `key_childdate` (`childid`,`date`)
);
And:
insert into history_childfees
...
on duplicate key update childid = 86615, date = '2019-03-22'
The columns that you update on duplicate key are exactly those of the UNIQUE KEY that you are using to identify duplicates. By design, we already know that the values do match... As a consequence, the query leaves duplicate records unmodified.
If I followed you correctly, you probably want:
insert into history_childfees
...
on duplicate key update amount = 50
I have a column with data that exceeds MySQL's index length limit. Therefore, I can't use an unique key.
There's a solution here to the problem without using an unique key: MySQL: Insert record if not exists in table
However, in the comments, people are having issues with inserting the same value into multiple columns. In my case, a lot of my values are 0, so I'll get duplicate values very often.
I'm using Node and node-mysql to access the database. I'm thinking I can have a variable that keeps track of all values that are currently being inserted. Before inserting, I check if the value is currently being inserting. If so, I'll wait until it finishes inserting, then continue execution as if the value was originally inserted. However, I feel like this will be very error prone.
Here's part of my table schema:
CREATE TABLE `links` (
`id` int(10) UNSIGNED NOT NULL,
`url` varchar(2083) CHARACTER SET latin1 COLLATE latin1_general_cs NOT NULL,
`likes` int(10) UNSIGNED NOT NULL,
`tweets` int(10) UNSIGNED NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
ALTER TABLE `links`
ADD PRIMARY KEY (`id`),
ADD KEY `url` (`url`(50));
I cannot put an unique key on url because it can be 2083 bytes, which is over MySQL's key size limit. likes and tweets will often be 0, so the linked solution will not work.
Is there another possible solution?
If you phrase your INSERT in a certain way, you can make use of WHERE NOT EXISTS to check first if the URL does not exist before completing the insert:
INSERT INTO links (`url`, `likes`, `tweets`)
SELECT 'http://www.google.com', 10, 15 FROM DUAL
WHERE NOT EXISTS
(SELECT 1 FROM links WHERE url='http://www.google.com');
This assumes that the id column is a primary key/auto increment, and MySQL will automatically assign a value to it.
Is it possible to update only a single field with ON DUPLICATE KEY UPDATE in a table with multiple fields?
If I have a table with three fields; key, cats, dogs where key is the primary key is it possible to update a record on duplicate key, changing only one field, (for my example cats) without changing the value in the other non-key fields (dogs). This is without knowing what the value of dogs from outside of the database at the time of insertion (i.e. I have a variable holding cats value, but not one holding dogs value)
INSERT INTO `myTable` (`key`,`cats`) VALUES('someKey1','Manx') ON DUPLICATE KEY UPDATE `cats` = 'Manx';
At the moment when I run something like this and the key already exists in the table dogs is set to NULL even when it had a value previously.
Gordon is right, it does not work the way I described. If you see this, it is not caused by the ON DUPLICATE UPDATE statement, but something else. Here is the proof:
CREATE TABLE IF NOT EXISTS `myTable` (
`key` varchar(20) NOT NULL default '',
`cats` varchar(20) default NULL,
`dogs` varchar(20) default NULL,
PRIMARY KEY (`key`)
)
The run
INSERT INTO `myTable` (`key`, `cats`, `dogs`) VALUES
('someKey1', NULL, 'jack-russell');
Then run
INSERT INTO `myTable` (`key`,`cats`) VALUES
('someKey1','Manx') ON DUPLICATE KEY UPDATE `cats` = 'manx';
Then check the table
I think you should try to UPSERT.
Please examine this:
INSERT INTO `item` (`item_name`, items_in_stock) VALUES( 'A', 27)
ON DUPLICATE KEY UPDATE `new_items_count` = `new_items_count` + 27
MySQL UPSERT
I've been getting this error from an insert on duplicate update query in MYSQL randomly every now and then.
Any idea what's going on? I can't seem to reproduce the error consistently it occurs sometimes and then sometimes not.
Here is the query in question:
INSERT INTO friendships (u_id_1,u_id_2,status) VALUES (?,?,'active') ON DUPLICATE KEY UPDATE id=LAST_INSERT_ID(id);
And the schema describing the table is:
DROP TABLE IF EXISTS `friendships`;
CREATE TABLE `friendships` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`u_id_1` int(11) NOT NULL,
`u_id_2` int(11) NOT NULL,
`status` enum('active','pending','rejected','blocked') DEFAULT 'pending' NOT NULL,
`initiatiator` enum('1','2','system') DEFAULT 'system' NOT NULL,
`terminator` enum('1','2','system') DEFAULT NULL,
`confirm_timestamp` timestamp DEFAULT NULL,
`created` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (`id`),
UNIQUE KEY (`u_id_1`,`u_id_2`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
Your ON DUPLICATE KEY UPDATE statement isn't helping you at all here.
You are taking the LAST_INSERT_ID, which is the auto inc of the last successfully inserted row, and trying to update the duplicated row with that id. This will always cause a duplicate primary (you're trying to change the id of some row to match the id of the last thing you added)
If your goal is to either
Insert a new row, or
Update an existing row with 'active'
Then
INSERT INTO friendships (u_id_1,u_id_2,status)
VALUES ( ? , ? ,'active')
ON DUPLICATE KEY UPDATE
status = 'active'; -- I changed this
A separate consideration is to check the source for duplicates. I had a simple audit table
INSERT INTO table
field1, field2, ... , field3
ON DUPLICATE KEY UPDATE row_id=row_id;
where field1 is an INDEX but not UNIQUE with row_ID as INTEGER UNSIGNED AUTO_INCREMENT PRIMARY KEY.
Ran for years, but an unexpected duplicate row triggered this error.
Fixed by de-duping the source.
Possibly a trivial point to many readers here, but it cost me some head-scratching (followed by a facepalm).
I need to insert records, but if the records exist do a replace instead. Here is what I am currently using:
$sessionDate = date("Y-m-d H:i:s");
foreach($tmpVP as $sessionVP) {
$res = mysql_query("INSERT INTO sessions
(sessionID,sessionDate,sessionVS,sessionVP)
VALUES('$sessionID','$sessionDate','$sessionVS',
'$sessionVP')") ;
}
What I really need is to update any records matching sessionID, sessionVS, and sessionVP and insert new records that don't match.
EDIT:
Table definition
CREATE TABLE `sessions` (
`ID` bigint(20) NOT NULL auto_increment,
`sessionID` varchar(36) NOT NULL,
`sessionDate` datetime NOT NULL,
`sessionUser` bigint(20) NOT NULL,
`sessionVS` varchar(255) NOT NULL,
`sessionVP` bigint(20) NOT NULL,
`reserved` int(11) NOT NULL,
PRIMARY KEY (`ID`),
KEY `ID` (`ID`)
) ENGINE=MyISAM AUTO_INCREMENT=88 DEFAULT CHARSET=utf8
sessionID, sessionVP, and sessionVS are not unique. Sample:
sessionID sessionDate sessionUser sessionVS sessionVP
0t1m58q9ktejuhqlrjqglcoia0 2010-06-20 09:20:53 0 111111 144268736
0t1m58q9ktejuhqlrjqglcoia0 2010-06-20 09:20:53 0 111111 144268819
0t1m58q9ktejuhqlrjqglcoia0 2010-06-20 09:20:53 0 111111 144268880
So, if I have a new record with 0t1m58q9ktejuhqlrjqglcoia0, 111111, and `144268880' I need to update row #3 instead of adding row #4.
Firstly you should add a unique index on (sessionID, sessionVP, sessionVS). You can do this using the following command:
CREATE UNIQUE INDEX ux_sessions_sessionid_sessionvs_sessionvp
ON sessions (sessionID, sessionVS, sessionVP)
Then there are two relatively simple ways to insert or update in MySQL. The first is to use ON DUPLICATE UPDATE:
INSERT INTO sessions
(sessionID,sessionDate,sessionVS,sessionVP)
VALUES
('$sessionID', '$sessionDate', '$sessionVS', '$sessionVP')
ON DUPLICATE KEY UPDATE sessionDate = '$sessionDate'
There other is to use REPLACE:
REPLACE INTO sessions
(sessionID,sessionDate,sessionVS,sessionVP)
VALUES
('$sessionID', '$sessionDate', '$sessionVS', '$sessionVP')
The second is slightly more concise, but has the disadvantage that it internally causes a delete followed by an insert.
There are also a few other issues:
You don't need both a primary key index and an ordinary index on ID. Remove the ordinary index as it is redundant.
You may have an SQL vulnerability. If you have not already validated the input you might want to consider protecting yourself by using mysql_real_escape_string or intval as appropriate. Alternatively you could look at using query parameters.
You are not checking for error conditions. Consider using trigger_error so that if your query has an error you can see what the error is. Seeing the error message can save you a lot of time debugging.
mysql_query("...") or trigger_error(mysql_error());
You might take a look at INSERT ... ON DUPLICATE KEY UPDATE: http://dev.mysql.com/doc/refman/5.0/en/insert-on-duplicate.html
Add an unique key on (sessionID, sessionVS, sessionVP), then use REPLACE instead of INSERT (just substitute the word, syntax is the same).
Based on your table structure, I mean the primary keys you can use
$res = mysql_query("REPLACE INTO sessions
(sessionID,sessionDate,sessionVS,sessionVP)
VALUES('$sessionID','$sessionDate','$sessionVS',
'$sessionVP')") ;
Are the values part of the primary key? If yes, take a look at: http://dev.mysql.com/doc/refman/5.0/en/insert-on-duplicate.html