We back up our mysql database every day around 2.00am.
yesterday, we did an accidental update to a column and that's affected the entire database instead of just one record.
Question :
Is it possible to get a column value from backup and use that to update the live database ?
One way would be to restore the backup to a separate database, query the column in question including the record's primary key.
Then transform the result of that's query into an update statement that you can execute on the live database.
I would advise to try this on a test environment first.
Related
I have a server in my company with mysql installed(on centos machine) in it. It already had data values inserted in it.
This morning when I tried to access my web application(which is connected by mysql) it gives me a database error.
Then I restarted mysql, I checked my database one table is automatically deleted and only 10 rows are inserted with all column value 1. In other table only one column is changed with same value on all row of that column.
I tried to run insert query but it shows timeout.And also phpmyadmin is slow.
I can guess that mysql is slow because mysql memory is full but why it deleted the row from one table and changed only one column of other table??
And is it possible to retreive my old database?
Any help would be apreciated.
I have the following issue related to I have in localhost(my computer) a Table in a database which I use to update the data for a month. Once data is correct, I need to update the Table in the database which resides in the server.
I use Navicat to do the work and it only transfer data deleting the actual database in the server and sending all the data from my localhost.
The problem is that the Table now has almost 300.000 records stored and it takes too long transfering the data leaving the database empty for some time.
Is there any way I could use that only update the data without deleting the whole table?
export local table with different name as mysqldump or just csv, 300k rows is not a big deal and use a different table now.
then upload the table 2 to db and use a query to update table 1 using table2 data.
I have a development server that is getting crowded.
I would like to see what date the databases have been accessed to determine what ones can be deleted. Is there a way to do this?
The only thing I found when searching was for postgredb:
How to get last access/modification date of a PostgreSQL database?
If you have a table that always gets values inserted you can add a trigger to the update/insert. Inside this trigger you can set the current timestamp in a dedicated database, including the name of the database from which the insert took place.
This way the only requirement of your database is that it supports triggers.
I'm getting data from an MSSQL DB ("A") and inserting into a MySQL DB ("B") using the date created in the MSSQL DB. I'm doing it with simple logics, but there's got to be a faster and more efficient way of doing this. Below is the sequence of logics involved:
Create one connection for MSSQL DB and one connection for MySQL DB.
Grab all of data from A that meet the date range criterion provided.
Check to see which of the data obtained are not present in B.
Insert these new data into B.
As you can imagine, step 2 is basically a loop, which can easily max out the time limit on the server, and I feel like there must be a way of doing this must faster and during when the first query is made. Can anyone point me to right direction to achieve this? Can you make "one" connection to both of the DBs and do something like below?
SELECT * FROM A.some_table_in_A.some_column WHERE
"it doesn't exist in" B.some_table_in_B.some_column
A linked server might suit this
A linked server allows for access to distributed, heterogeneous
queries against OLE DB data sources. After a linked server is created,
distributed queries can be run against this server, and queries can
join tables from more than one data source. If the linked server is
defined as an instance of SQL Server, remote stored procedures can be
executed.
Check out this HOWTO as well
If I understand your question right, you're just trying to move things in the MSSQL DB into the MySQL DB. I'm also assuming there is some sort of filter criteria you're using to do the migration. If this is correct, you might try using a stored procedure in MSSQL that can do the querying of the MySQL database with a distributed query. You can then use that stored procedure to do the loops or checks on the database side and the front end server will only need to make one connection.
If the MySQL database has a primary key defined, you can at least skip step 3 ("Check to see which of the data obtained are not present in B"). Use INSERT IGNORE INTO... and it will attempt to insert all the records, silently skipping over ones where a record with the primary key already exists.
I have a table that has 7000 rows,
I added a new column to this table
The table has a mysql DateTime so.
When i updated the table to fill in this new table it updated the datetime,
I took an sql dump just before i did the update so now i need to use the sql dump to revert the datetime back (and only that column).
How do i do that?
There are a couple ways I can think of to do this off the top of my head.
First is to create another mysql database and load the dump into that database (make sure it's not going to load into the first database from a use commmand in the dump), and then use the data from that database to construct the update queries for the first.
The second, easier, more hackish way, is to open the dump in a text editor, pull out just that table, and find and replace to make update statements for just that column based on primary key instead of inserts. You'd need to be able to find and replace on patterns.
A third way would be to load the dump in an abstract sql tool letting it do the parsing for you, and write new queries from the data in the abstract syntax trees.
A fourth, again hackish, possibility, if this isn't a live system, is to rollback and re-perform the more recent transformations (only if they are simple).
Restore the dump to a second table. Select the ID and datetime from that table. Use those results to update the rows in the original table corresponding to the IDs you got.