I've just create table and add data to rows. Now I need to delete some rows, but I can't do it using mysql-wokbench. Delete rows is disabled. Also I can't edit data, when I choose "Edita table Data". Can you help me? Why is it so?
I CAN NOT DELETE BY THE HAND, USING THAT WORKBENCH. BUT I CAN'T FROM SQL QUERY.
In order to be able to edit the result set from a query like SELECT * from table the table must have a primary key defined, as this is what WB uses to find a certain record.
SHOW GRANTS FOR CURRENT_USER;
See if you have the rights for that.
Related
I have two MySQL database k_db1 and k_db2 on a single server.
In k_db1, I have k_db1.table1 and k_db1.table2.
In k_db2, I have k_db2.table3 and k_db2.table4.
I want to create a third database k_db3 where I copy/paste tables of others databases.
It will result in k_db3.db1-table1, k_db3.db1-table2, k_db3.db2-table3, k_db3.db2-table4. I want to transfer data, indexes etc... and I don't want to delete k_db1 and k_db2 tables in the process. It must duplicate datas.
Do you know a way to do this just with SQL command?
Thanks in advance for your help.
You can try something like this:
DROP TABLE IF EXISTS k_db3.db1_table_1;
CREATE TABLE k_db3.db1_table_1 AS
SELECT * FROM db1.table_1;
Then you can recreate the indexes on the new table via ALTER TABLE statements.
Also I would avoid using - in table names.
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 need a little advice concerning a MySQL operation:
There is a database A wich yields several tables. With a query I selected a set of entries out of this database to copy these results into another table of database B.
Now the table in database B contains the results of my query on database A.
For instance the query is:
SELECT names.name,ages.age FROM A.names names A.ages ages WHERE ages.name = name.name;
And to copy these results into database B I would run:
INSERT INTO B.persons (SELECT name,age FROM A.names names A.age age WHERE age.name = name.name);
Here's my question: When the data of database A has changed I want to run an "update" on the table of database B.
So, the easy and dirty approach would be: Truncate the table in database B, re-run the query on database A and copy the result back to database B.
But isn't there a smarter way so that only new result rows of that query will be copied and those entries in database B which are not in database A anymore get deleted?
In short: Is there a way to "augment" the table of database B with new entries and "prune" old entries out?
Thanks for your help
I would do two things:
1) Ensure you have a primary key that's either an integer or a unique combination of columns at a minimum in database B
2) Use logical deletes instead of physical deletes i.e. have a boolean deleted column
Point 2 ensures you never have to delete and lose data, you just update the flag and in your queries put where deleted = 0 or where deleted is null.
When combined with a primary key it means everything can be handled easily by an INSERT ... WITH DUPLICATE KEY which will insert new rows and update existing ones - which means it can perform your 'deletes' at the same time too.
What you describe sounds like you want to replicate the table. There is no simple quick fix for what you describe. You could of course write some application logic to do it but it would not be so efficient as it would have to compare each entry in each table and then delete or update accordingly.
One solution would be to setup a foreign-key index between A and B and cascade updates and deletes to B. But this would only partly solve the problem. It would drop rows in B if they were deleted in A and it would update a key column in B if it were updated in A. But it would not update the other columns. Note also that this would require your table type to be INNODB.
Another would be to run inserts on B with A's values but use
INSERT ON DUPLICATE KEY UPDATE....
Again this would work fine for updates but not for Deletes.
You could try to setup actual MySQL replication but this is perhaps beyond the scope of your problem and is more involved.
Finally you could set up the foreign key index as described above and write a trigger that whenever an updates is applied to A then the corresponding key row in B is also updated. This seems like a plausible solution for you while not the cleanest I would admit.
It would seem that a small batch script run periodically on which ever environment your running on to duplicate the table would be the best to achieve what you are looking for.
Is there a way to do this?
In case the DBMS command history got cleaned or, in my case, when many ALTER TABLE were used in the course of time.
I'm using MySQL.
Yes, it is as simple as
SHOW CREATE TABLE yourtable;
This will include all the subsequent ALTER TABLE statements. You cannot retrieve the table's original state.
Here is the relevant documentation
I am having two tables. For example one is Login and the other is calculation. In the login table I am having fields username and password. In calculation I am having username and flag.
Now when any user is added in the login table I want make entry for that user in calculation table also.
How can I proceed for this?
Why not have the flag in the Login table?
In MySQL you should be able to set a 'trigger' on the insert operation on the login table, that can do the second insert for you. See:
http://dev.mysql.com/doc/refman/5.0/en/triggers.html
You might want to handle deletes and/or updates (change of username?) in the same way.
Meder's answer above will certainly work but prehaps the strategy you are looking for involves triggers; this will allow you to automatically update other info when ever row on a specific table is inserted, updated or deleted.
You only have to create trigger once and then any insert from any source to your LOGIN tbale will also update your CALCULATE table.
My SQL Documentation details the statement here.