I'm trying to reset the seed for an autoincrement field in SQLITE using AIR/ActionScript/Flex 4.5.
I'm doing what should normally work:
DELETE FROM SQLITE_SEQUENCE WHERE NAME = 'myTable'
I've checked that the database actually contains a SQLITE_SEQUENCE table. I'm able to execute the above statement without errors directly via the Firefox SQLITE plugin (SQLite Manager).
However, when I try to do the same using actionscript, I get an error:
No such table 'SQLITE_SEQUENCE'.
All I could find in searching around was this one guy who posted everywhere he could find - only to be left without an answer:
here
and
here
and
here
Any ideas?
sqlite_sequence table is not created, until you define at least one autoincrement and primary key column in your schema.
You should to insert "Auto increment" to primary key column
at least to one table,
Then SQLite is creating "SQLITE_SEQUENCE" table.
To get all tables have Auto increment:
SELECT * FROM SQLITE_SEQUENCE;
Related
I have migrated a database using structure only
In this database I have a table called hash that is empty, of course.
This table is being used by tons of other tables through foreign key.
I have another table called hash_copy that has been just copied from another database and is full of records (500'000 records).
I tried to replace one table by another with the following SQL Statement
SET FOREIGN_KEY_CHECKS=0;
RENAME TABLE hash to hash_empty, hash_copy to hash;
SET FOREIGN_KEY_CHECKS=1;
Problem is that now all my foreing keys are poiting to hash_empty which is what I was trying to avoid.
To sumup
I'd like to turn off Foreign Keys just to swap one table for another (throw the empty away and plug the full of records) without having to go through all the tables that makes references to it.
Is this possible?
Thanks in advance.
As per the comments, a table can be copied to another table like:
INSERT INTO hash SELECT * from hash_copy
More generally, the insert-select syntax works like as you would expect; you can specify column names (INSERT INTO hash(col1, col2, col3)) and include any SELECT syntax you normally would (functions, joins, where clauses, etc).
I've tried to execute the following ALTER TABLE statement:
ALTER TABLE `my_table` ADD COLUMN `new_column` LONGTEXT NULL DEFAULT NULL AFTER `old_column`;
During the execution of the script I've got
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
It appears that this left database in inconsistent state, since no new field was added, and when I try to execute the script again, I'm getting this strange error.
com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Table 'my_db/#sql-ib520' already exists
I do not have #sql-ib520 table in my database, so to my understanding it must be some temp table created by the MySQL.
Does anyone encountered this error before, and how could I solve it?
Thanx
Edit
I've tried the script suggested by Alex, but I had not worked:
drop table `#mysql50##sql-ib520`;
ERROR 1051 (42S02): Unknown table 'my_db.#mysql50##sql-ib520'
Update
I'm using Amazon RDS with MySQL 5.6.12
I'm using an AWS RDS instance as well, and did a ton of reading on this problem. While I didn't find a great solution, here's how I fixed it by only replacing one table instead of the entire database.
If you run this command:
SELECT * FROM INFORMATION_SCHEMA.INNODB_SYS_TABLES
you can see the full list of database tables, including the orphaned table, which isn't normally visible. The two problem tables for me were:
ID NAME
407 my_database/#sql-ib379
379 my_database/users
because I was attempting to ALTER my users table when the DB crashed. Now, as mentioned above, I couldn't run any further ALTER TABLE commands because it was trying to create the same temporary table for any subsequent queries. I tried everything to DROP the orphaned table, but with the 'my_database/' part, it didn't seem possible. I also didn't want to drop and recreate my entire database, and I noticed that the orphaned table is referencing an internal ID of the users table (#sql-ib379), so I figured I would just swap it out. Here's a little MySQL script that did the trick for me:
-- temporarily disable foreign key checks
SET foreign_key_checks = 0;
-- replace this line with query to create a structural copy of the users table
-- named users_copy, including foreign keys if you use them
-- copy everything from original table into new table
INSERT INTO `users_copy` SELECT * FROM `users`;
Make sure everything looks ok, and then run:
-- rename the existing table
RENAME TABLE `users` TO `users_backup`;
-- in case the copy process took some time, and there were additional rows added
-- to the original table, grab them and put them into the copy table
INSERT INTO `users_copy` SELECT * FROM `users_backup` WHERE `users_backup`.id > (SELECT MAX(id) FROM `users_copy`);
-- finally, rename the copy table to the original table name
RENAME TABLE `users_copy` TO `users`;
- re-enable foreign key checks
SET foreign_key_checks = 1;
If you are not using foreign keys, you should be good to go now. I would recommend keeping the backup table around for a bit just in case, but once you remove that backup table, it should remove the orphaned table as well. If you are using foreign keys however, it is very important that you update any references to the original table name (in this case, users)! Depending on how you have your foreign keys setup, other tables that were dependent on users will now reference users_backup, which could cause problems with lost data.
Hope this helps.
After all, since I'm using AWS RDS instance, the script recommended by Alex did not work.
MySQL documentation also recommends this script, you can find more info here about orphaned intermediate tables.
For AWS RDS I've found only one post with no solution provided by Amazon staff. You might want to follow this post in case some solution is provided.
So, at the moment, my only solution was to dump the existing database and create a new one.
I am using cfwheels (coldfusion orm framework).
I recently moved some data from my previous host to a new one. Now I am trying to insert into a table, but am getting an error message: "Error Executing Database Query.
Duplicate entry '13651' for key 'PRIMARY'"
I looked into the database and it appears a record with id 13651 already exists. So I think the problem is with mysql generating the right auto increment value.
It seems Auto_Increment value is damaged or not set to max value in that column. It's possible due to bulk insert.
So as per solution, set the maximum PK value + 1 as new AUTO_INCREMENT value. Now when you insert the records in this table, they will automatically pick the next incremented correctly.
ALTER.TABLE tablename AUTO_INCREMENT = value
Is the rest of the data for that record, and the one you are trying to insert, the same? If you you might just need to tell the ORM to replace that value?
If primary key has auto increment attribute turned on, do not insert it manually. remove that primary key part from your insert query (whatever the syntax according to the taste of your ORM framework).
Ihave been developing an app for some time. This involves entering and deleteing alot of useless data in the tables. Now that I want to go to production I want to get rid of all the data but also restore all the 'IDs' ( primary keys ) to 0 so that the live system can start fresh with sensible ID's like 1,2,3 etc.
Using MySQL and PHP / Codeigniter
Many Many Thanks for yoru help !
I would normally use TRUNCATE - this both removes the data and resets the AUTO_INCREMENT.
Note that MySQL will perform a row by row deletion if there is a foreign key relationship, which is quite convenient (compared to SQL Server).
If your pk is autoincrement, you can do
ALTER TABLE tbl AUTO_INCREMENT =1
Make sure table is empty before executing the query.
I have a table that is in production. I realize that some of the columns should be unique. Is it safe to go into phpMyAdmin and change those columns to make it unique?
ALTER TABLE `foo` ADD UNIQUE ( `bar` )
Follow the below steps to apply unique column value from phpmyadmin panel:
Go to the table structure. Click on the unique keyword as like below -
Click on the ok from confirmation box -
Unique value constraint for column will apply.
Or you can run mysql query:
ALTER TABLE user ADD UNIQUE(email);
You do not have duplicates -> will apply the key without issues
You do have duplicates -> will give an error message, nothing happened to your data
All is unique, except several rows with NULL in them, unique constraint is still applied, as NULL is not checked when checking for unique values (you can have the entire table have a NULL value in a unique field without any error message).
One more thing, if you have a prod DB, you must also have a dev DB which you can test on without fear, right?
If there are already some duplicate values in those columns, then this will generate an error. If there aren't any duplicate values in those columns, then you will be fine.
It will only be a problem if the pre-existing values on the table are not unique, otherwise I don't think there will be any problem.
I had this problem and my values were not unique. I also couldn't find an easy way to edit this problem in PHPMyAdmin. Here's how I solved it:
I clicked into the table I needed to update
I exported the table, changing it to be a CSV export and then edited
it manually to update the non-unique values.
Making sure I was still in the table I had exported (because I
wanted to keep the headers intact), I imported my newly saved CSV
Hope that saves someone some time in the future.