MySQL duplicate entry error even though there is no duplicate entry - mysql

I am using MySQL 5.1.56, MyISAM. My table looks like this:
CREATE TABLE IF NOT EXISTS `my_table` (
`number` int(11) NOT NULL,
`name` varchar(50) NOT NULL,
`money` int(11) NOT NULL,
PRIMARY KEY (`number`,`name`)
) ENGINE=MyISAM;
It contains these two rows:
INSERT INTO `my_table` (`number`, `name`, `money`) VALUES
(1, 'S. Name', 150), (2, 'Another Name', 284);
Now I am trying to insert another row:
INSERT INTO `my_table` (`number`, `name`, `money`) VALUES
(2, 'S. Name', 240);
And MySQL just won't insert it while telling me this:
#1062 - Duplicate entry '2-S. Name' for key 'PRIMARY'
I really don't understand it. The primary key is on the first two columns (both of them), so the row I am trying to insert HAS a unique primary key, doesn't it?
I tried to repair the table, I tried to optimize the table, all to no avail. Also please note that I cannot change from MyISAM to InnoDB.
Am I missing something or is this a bug of MySQL or MyISAM? Thanks.
To summarize and point out where I think is the problem (even though there shouldn't be):
Table has primary key on two columns. I am trying to insert a row with a new combination of values in these two columns, but value in column one is already in some row and value in column two is already in another row. But they are not anywhere combined, so I believe this is supposed to work and I am very confused to see that it doesn't.

Your code and schema are OK. You probably trying on previous version of table.
http://sqlfiddle.com/#!2/9dc64/1/0
Your table even has no UNIQUE, so that error is impossible on that table.
Backup data from that table, drop it and re-create.
Maybe you tried to run that CREATE TABLE IF NOT EXIST. It was not created, you have old version, but there was no error because of IF NOT EXIST.
You may run SQL like this to see current table structure:
DESCRIBE my_table;
Edit - added later:
Try to run this:
DROP TABLE `my_table`; --make backup - it deletes table
CREATE TABLE `my_table` (
`number` int(11) NOT NULL,
`name` varchar(50) NOT NULL,
`money` int(11) NOT NULL,
PRIMARY KEY (`number`,`name`),
UNIQUE (`number`, `name`) --added unique on 2 rows
) ENGINE=MyISAM;

I know this wasn't the problem in this case, but I had a similar issue of "Duplicate Entry" when creating a composite primary key:
ALTER TABLE table ADD PRIMARY KEY(fieldA,fieldB);
The error was something like:
#1062 Duplicate entry 'valueA-valueB' for key 'PRIMARY'
So I searched:
select * from table where fieldA='valueA' and fieldB='valueB'
And the output showed just 1 row, no duplicate!
After some time I found out that if you have NULL values in these field you receive these errors. In the end the error message was kind of misleading me.

I had a similar issue, but in my case it turned out that I used case insensitive collation - utf8_general_ci.
Thus, when I tried to insert two strings which were different in a case-sensitive comparison, but the same in the case-insensitive one, MySQL fired the error and I couldn't understand what a problem, because I used a case-sensitive search.
The solution is to change the collation of a table, e.g. I used utf8_bin which is case-sensitive (or utf8_general_cs should be appropriate one too).

In case this helps anyone besides the OP, I had a similar problem using InnoDB.
For me, what was really going on was a foreign key constraint failure. I was referencing a foreign key that did not exist.
In other words, the error was completely off. The primary key was fine, and inserting the foreign key first fixed the problem. No idea why MySQL got this wrong suddenly.

Less common cases, but keep in mind that according to DOC https://dev.mysql.com/doc/refman/5.6/en/innodb-online-ddl-limitations.html
When running an online ALTER TABLE operation, the thread that runs the ALTER TABLE operation will apply an “online log” of DML operations that were run concurrently on the same table from other connection threads. When the DML operations are applied, it is possible to encounter a duplicate key entry error (ERROR 1062 (23000): Duplicate entry), even if the duplicate entry is only temporary and would be reverted by a later entry in the “online log”. This is similar to the idea of a foreign key constraint check in InnoDB in which constraints must hold during a transaction.

In my case the error was caused by the outdated schema, one column was originally varchar(50) but the dump I was trying to import was created from a modified version of the schema that has varchar(70) for that column (and some of the entries of that field where using more than 50 chars).
During the import some keys were truncated and the truncated version was not unique anymore. Took a while to figure that out, I was like "but this supposedly duplicated key doesn't even exist!".

Try with auto increment:
CREATE TABLE IF NOT EXISTS `my_table` (
`number` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(50) NOT NULL,
`money` int(11) NOT NULL,
PRIMARY KEY (`number`,`name`)
) ENGINE=MyISAM;

Your code is work well on this demo:
http://sqlfiddle.com/#!8/87e10/1/0
I think you are doing second query (insert...) twice. Try
select * from my_table
before insert new row and you will get that your data already exist or not.

i have just tried, and if you have data and table recreation wouldnt work, just alter table to InnoDB and try again, it would fix the problem

In case anyone else finds this thread with my problem -- I was using an "integer" column type in MySQL. The row I was attempting to insert had a primary key with a value larger than allowed by integer. Switching to "bigint" fixed the problem.

As per your code your "number" and "Name" are primarykey and you are inserting S.NAME in both row so it will make a conflict. we are using primarykey for accessing complete data. here you cant access the data using the primarykey 'name'.
im a beginner and i think it might be the error.

In my case the error was very misleading. The problem was that PHPMyAdmin uses "ALTER TABLE" when you click on the "make unique" button instead of "ALTER IGNORE TABLE", so I had to do it manually, like in:
ALTER TABLE mytbl ADD UNIQUE (columnName);

This problem is often created when adding a column or using an existing column as a primary key. It is not created due to a primary key existing that was never actually created or due to damage to the table.
What the error actually denotes is that a pending key value is blank.
The solution is to populate the column with unique values and then try to create the primary key again. There can be no blank, null or duplicate values, or this misleading error will appear.

For me a noop on table has been enough (was already InnoDB):
ALTER TABLE $tbl ENGINE=InnoDB;

tl;dr: my view showed my table was empty but the view excluded existing rows.
I had the same problem but mine was because I was inserting the same test rows I had used before. When I checked to see if my table was empty, I used a view that excluded different tenants so the search came back empty. When I checked the actual table, the previous records were still there.
Once I had deleted the existing records, the insert worked. Only half a day of frustration lost to this one...

Had this error, when adding a composite primary key that is ADD PRIMARY KEY (column1, column2, ...) The value of all the columns in that row must not be duplicated.
For Example:
You do ADD PRIMARY KEY (name, country, number)
name
country
number
collin
Uk
5
collin
Uk
5
This will throw an error #1062 - Duplicate entry 'collin-UK-5' for key 'PRIMARY' because the columns combined have duplicate
So if you see this format of error just check and ensure that the columns you want to add a composite primary key to combined don't have duplicates.

Another reason you may be getting this error is because the same restriction exists in another related table, and they Keyname on the related table has the exact same name. I've had this happen once and it was quite difficult to identify.
i.e. if you have a trigger that inserts data to a different table (the "related" table) with the same restriction and same Keyname, MySQL will not include the name of the table throwing the error, only the Keyname.

As looking on your error #1062 - Duplicate entry '2-S. Name' for key 'PRIMARY' it is saying that you use primary key in your number field that's why it is showing duplicate Error on Number Field.
So Remove this primary Key then it inset duplicate also.

Related

Duplicate entry for primary key on MySQL

My table just has single column ID (passwords for admin Log-in)
Because this code runs every time that program starts, I can prevent errors occurs on creating database and creating tables by using IF NOT EXIXTS statement.
Since adminLogin table should be initial first time, When user re-run the program, the Duplicate entry for primary key error occurs.
I used IF NOT EXISTS for inserting into table, But there is some another error!
My table:
Error:
You are trying to insert same value.
PK should be unique.
SET ID as autoincrement.
CREATE TABLE `table_code` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`your_column` varchar(45) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=latin1;
Another possibility
INSERT INTO adminLogin(ID) VALUES(100) ON DUPLICATE KEY UPDATE ID=ID;
You can use INSERT IGNORE instead.
INSERT IGNORE INTO ADMINLOGIN VALUES(200);
INSERT IGNORE
INSERT ... ON DUPLICATE KEY UPDATE ...
REPLACE INTO can all work without erroring. Depending on your needs, some may be a better use than others.
Here's a brief pros and cons of each:
INSERT IGNORE:
Pros: Easy to write
Cons: if data that is being inserted is newer the older data will be preserved
INSERT ... ON DUPLICATE KEY UPDATE ...
Pros: Can Insert or update specific columns that could have more recent data
Cons: A little harder to write the query for
REPLACE INTO
Pros: Can insert and update columns that could have more recent data. Faster than Insert, on duplicate key update.
Cons: Overwrites every column even though only some columns may have newer data. IF you are inserting multiple rows replace into could potentially overwrite data for existing rows that you don't really want to overwrite.

How to don´t repeat values stored in database

I´m creating a database addrees and I want to know what I need to set in Mysql to don´t store repeat values?
Like
Addrees 1 ("teste",1,new york,eua);
Addrees 2 ("teste",1,new york,eua);
If this happen my database will not store.
So what I need to do?
To alter an already existing table, run this MySQL command:
alter table yourtablename add unique index(firstcolumn, secondcolumn, thirdcolumn, fourthcolumn);
That'll add the unique constraint to the specified columns. Here's how to specify such a constraint in the CREATE TABLE.
CREATE TABLE buyers (
buyer_id INT UNSIGNED NOT NULL,
first_name CHAR(19) NOT NULL,
last_name CHAR(19) NOT NULL,
age SMALLINT NOT NULL,
post_code SMALLINT NOT NULL,
UNIQUE idx_flname_age (first_name,last_name,age)
);
The primary key constraint will do this too, as mentioned by #Ajeesh
EDIT:
As per the suggestion in the comment, if you want to avoid errors generated by this unique constraint, you have three good options:
INSERT IGNORE
and
INSERT...ON DUPLICATE KEY UPDATE
and
REPLACE
INSERT IGNORE will not do anything if the insert violates the unique constraint, except log a harmless warning. The table will be left as is, and no error would be reported. This may be desireable in some cases.
More commonly is the second option, ON DUPLICATE KEY UPDATE, which says "Well, if the key already exists, then update that key's row like this instead."
And lastly is REPLACE, which will, if the key already exists, delete the row, then do an INSERT as normal. If the key did not exist previously, it will simply act as an INSERT.
This stack overflow answer has some examples.
"INSERT IGNORE" vs "INSERT ... ON DUPLICATE KEY UPDATE"
You need to call these fields a UNIQUE_KEY
To make a column to be distinct you need to have Primary Key constraint/Unique Key. Primary key is used for relating one table with another and it's values should not be NULL. But in your case you can have Unique constraint to store only unique/distinct values.

MySQL INSERT with a Composite Key

Edit: I am a muppet. So after careful trawling of the rows I was trying to insert, there was a bug in my code which meant empty strings were being inserted. Because this happened more than once, MySQL quite rightly threw an error because I was trying to insert the same data again. Sorry for any time wasted! Mods, feel free to delete this.
My table structure is as follows:
CREATE TABLE IF NOT EXISTS `foo` (
`user` varchar(80) NOT NULL,
`group` varchar(20) NOT NULL,
`completed` int(1) NOT NULL,
PRIMARY KEY (`user`,`group`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
Now when I try to do a MySQL Insert, it throws errors saying that I have duplicates (which with the key set up, won't work). What I don't get is why I am seeing those errors. I know that I am not inserting a duplicate of those composite values (although some values will appear many times in the group column.
An example of my insert: INSERT INTO food(user, group, completed) VALUES ('user1', 'groupA', '0'),('user2', 'groupB', '0'),('user3', 'groupA', '0');
So the composite of user and group are definitely unique. So why does it fail complaining that I am trying to insert a non unique key?
The error I get is: #1062 - Duplicate entry 'groupA' for key 1. It seems to be fine if I am trying to insert one or two rows at a time, but I am currently trying to insert 140 rows in one go.
Thanks!
You can't use "group" as a column name because it's a reserved word.
I altered the column name and your query works just fine, as it should.
Since you've completely "obfuscated" your actual SQL, it's entirely possible that you edited out a typo that's responsible for your error.
Your key is not composite. I fit was composite error would be like this
ERROR 1062 (23000): Duplicate entry 'user1-groupA' for key 'PRIMARY'
Notice, it displays values of all columns that make index.
I think You have another index just on column group.

How do I mitigate duplicate row inserts based on a non-key column?

I need to import data from one MySQL table into another. The old table has a different outdated structure (which isn't terribly relevant). That said, I'm appending a field to the new table called "imported_id" which saves the original id from the old table in order to prevent duplicate imports of the old records.
My question now is, how do I actually prevent duplicates? Due to the parallel rollout of the new system with the old, the import will unfortunately need to be run more than once. I can't make the "import_id" field PK/UNIQUE because it will have null values for fields that do not come from the old table, thereby throwing an error when adding new fields. Is there a way to use some type of INSERT IGNORE on the fly for an arbitrary column that doesn't natively have constraints?
The more I think about this problem, the more I think I should handle it in the initial SELECT. However, I'd be interested in quality mechanisms by which to handle this in general.
Best.
You should be able to create a unique key on the import_id column and still specify that column as nullable. It is only primary key columns that must be specified as NOT NULL.
That said, on the new table you could specify a unique key on the nullable import_id column and then handle any duplicate key errors when inserting from the old table into the new table using ON DUPLICATE KEY
Here's a basic worked example of what I'm driving at:
create table your_table
(id int unsigned primary key auto_increment,
someColumn varchar(50) not null,
import_id int null,
UNIQUE KEY `importIdUidx1` (import_id)
);
insert into your_table (someColumn,import_id) values ('someValue1',1) on duplicate key update someColumn = 'someValue1';
insert into your_table (someColumn) values ('someValue2');
insert into your_table (someColumn) values ('someValue3');;
insert into your_table (someColumn,import_id) values ('someValue4',1) on duplicate key update someColumn = 'someValue4';
where the first and last inserts represent inserts from the old table and the 2nd and 3rd represent inserts from elsewhere.
Hope this helps and good luck!

What could cause duplicate ids on a auto increment primary key field (mysql)?

RESOLVED
From the developer: the problem was that a previous version of the code was still writing to the table which used manual ids instead of the auto increment. Note to self: always check for other possible locations where the table is written to.
We are getting duplicate keys in a table. They are not inserted at the same time (6 hours apart).
Table structure:
CREATE TABLE `table_1` (
`sales_id` int(10) unsigned NOT NULL auto_increment,
`sales_revisions_id` int(10) unsigned NOT NULL default '0',
`sales_name` varchar(50) default NULL,
`recycle_id` int(10) unsigned default NULL,
PRIMARY KEY (`sales_id`),
KEY `sales_revisions_id` (`sales_revisions_id`),
KEY `sales_id` (`sales_id`),
KEY `recycle_id` (`recycle_id`)
) ENGINE= MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=26759 ;
The insert:
insert into `table_1` ( `sales_name` ) VALUES ( "Blah Blah" )
We are running MySQL 5.0.20 with PHP5 and using mysql_insert_id() to retrieve the insert id immediately after the insert query.
I have had a few duplicate key error suddenly appear in MySql databases in the past even though the primary key is defined and auto_increment. Each and every time it has been because the table has become corrupted.
If it is corrupt performing a check tables should expose the problem. You can do this by running:
CHECK TABLE tbl_name
If it comes back as corrupt in anyway (Will usually say the size is bigger than it actually should be) then just run the following to repair it:
REPAIR TABLE tbl_name
Does the sales_id field have a primary (or unique) key? If not, then something else is probably making inserts or updates that is re-using existing numbers. And by "something else" I don't just mean code; it could be a human with access to the database doing it accidentally.
As the other said; with your example it's not possible.
It's unrelated to your question, but you don't have to make a separate KEY for the primary key column -- it's just adding an extra not-unique index to the table when you already have the unique (primary) key.
We are getting duplicate keys in a table.
Do you mean you are getting errors as you try to insert, or do you mean you have some values stored in the column more than once?
Auto-increment only kicks in when you omit the column from your INSERT, or try to insert NULL or zero. Otherwise, you can specify a value in an INSERT statement, over-riding the auto-increment mechanism. For example:
INSERT INTO table_1 (sales_id) VALUES (26759);
If the value you specify already exists in the table, you'll get an error.
Please post the results of this query:
SELECT `sales_id`, COUNT(*) AS `num`
FROM `table_1`
GROUP BY `sales_id`
HAVING `num` > 1
ORDER BY `num` DESC
If you have a unique key on other fields, that could be the problem.
If you have reached the highest value for your auto_increment column MySQL will keep trying to re-insert it. For example, if sales_id was a tinyint column, you would get duplicate key errors after you reached id 127.