I have an sql file with alot of create, alterings and modifies to a database. If I need to back out at some point (up to a day maybe) after executing the sql script, is there an easy way to do that? For example, is there any tool to read an sql script and produce a 'rollback' script from it?
I am using sqlyog aswell, in case there happens to be any such features built-in (I havn't found any)
No, sorry, there are many statements that cannot be reversed from looking at the SQL command.
DROP TABLE (what was in the table that dropped?)
UPDATE mytable SET timestamp = NOW() (what was the timestamp before?)
INSERT INTO mytable (id) VALUES (NULL) (assuming id is auto-increment, what row was created?)
Many others...
If you want to recover the database from before your day's worth of changes, take a backup before you begin changing it.
You can also do point-in-time recovery using binary logs, to restore the database to any moment since your last backup.
Related
I have a mysql table which has an auto increment id field(id), videoid(int) and userid(int). The site is live now. I forgot to put a date/time field there. now there are some data here. Is it possible to get the insert time for all the existing data?
I have another table which gets reset every week by a cron job. Something wrong happened last week and now I badly need those data. Is there any option by which I can get any kind of backup from a certain date? Does mysql has auto backup or something like that?
If you have access to the binary log, you can get the insert statements by using mysqlbinlog. Read more about it in the manual.
The output from mysqlbinlog can be re-executed (for example, by using it as input to mysql) to redo the statements in the log. This is useful for recovery operations after a server crash.
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 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.
I am working with multiple databases in a PHP/MySQL application. I have development, testing, staging and production databases to keep in sync.
Currently we're still building the thing, so it's easy to keep them in sync. I use my dev db as the master and when I want to update the others I just nuke them and recreate them from mine. However, in future once there's real data I can't do this.
I would like to write SQL scripts as text files that I can version with the PHP changes that accompany them in svn, then apply the scripts to each db instance as I update them.
I would like to use transactions so that if there are any errors during the script, it will roll back any partial changes made. All tables are InnoDB
When I try to add a column that already exists, and add one new column like this:
SET FOREIGN_KEY_CHECKS = 0;
START TRANSACTION;
ALTER TABLE `projects` ADD COLUMN `foo1` varchar(255) NOT NULL after `address2`;
ALTER TABLE `projects` ADD COLUMN `foo2` varchar(255) NOT NULL after `address2`;
COMMIT;
SET FOREIGN_KEY_CHECKS = 1;
... it still commits the new column even though it failed to add the first one, of course, because I issued COMMIT instead of ROLLBACK.
I need it to issue the rollback command conditionally upon error. How can I do this in an adhoc SQL script?
I know of the 'declare exit handler' feature of stored procs but I don't want to store this; I just want to run it as an adhoc script.
Do I need to make it into a stored proc anyway in order to get conditional rollbacks, or is there another way to make the whole transaction atomic in a single adhoc SQL script?
Any links to examples welcome - I've googled but am only finding stored proc examples so far
Many thanks
Ian
EDIT - This is never going to work; ALTER TABLE causes an implicit commit when encountered: http://dev.mysql.com/doc/refman/5.0/en/implicit-commit.html Thanks to Brian for the reminder
I learned the other day that data definition language statements are always acted on in MySQL and cause transactions to be committed when they are applied. I think you'll probably have to do this interactively if you want to be sure of success.
I can't find the question on this website where this was discussed (it was only a couple of days ago).
If you need to keep multiple databases in synch, you could look into replication. Although replication isn't to be trifled with, it may be what you need. See http://dev.mysql.com/doc/refman/5.0/en/replication-features.html
I have a live database that had some data deleted from it and I need that data back. I have a very recent copy of that database that has already been restored on another machine. Unrelated changes have been made to the live database since the backup, so I do not want to wipe out the live database with a full restore.
The data I need is small - just a dozen rows - but those dozen rows each have a couple rows from other tables with foreign keys to it, and those couple rows have god knows how many rows with foreign keys pointing to them, so it would be complicated to restore by hand.
Ideally I'd be able to tell the backup copy of the database to select the dozen rows I need, and the transitive closure of everything that they depend on, and everything that depends on them, and export just that data, which I can then import into the live database without touching anything else.
What's the best approach to take here? Thanks.
Everyone has mentioned sp_generate_inserts. When using this, how do you prevent Identity columns from messing everything up? Do you just turn IDENTITY INSERT on?
I've run into similar situations before, but found that doing it by hand worked the best for me.
I restored the backup to a second server and did my query to get the information that I needed, I then build a script to insert the data sp_generate_inserts and then repeated for each of my tables that had relational rows.
In total I only had about 10 master records with relational data in 2 other tables. It only took me about an hour to get everything back the way it was.
UPDATE To answer your question about sp_generate_inserts, as long as you specify #owner='dbo', it will set identity insert to ON and then set it to off at the end of the script for you.
you'll have to restore by hand. The sp_generate_inserts is good for new data. but to update data I do it this way:
SELECT 'Update YourTable '
+'SET Column1='+COALESCE(''''+CONVERT(varchar,Column1Name)+'''','NULL')
+', Column2='+COALESCE(''''+CONVERT(varchar,Column2Name)+'''','NULL')
+' WHERE Key='+COALESCE(''''+CONVERT(varchar,KeyColumn)+'''','NULL') FROM backupserver.databasename.owner.YourTable
you could create inserts this way too, but sp_generate_inserts is better. Watch those identity values, and good luck (I've had this problem before and know where you're at right now).
useful queries:
--find out if there are missing rows, and which ones
SELECT
b.key,c.key
from backupserver.databasename.owner.YourTable b
LEFT OUTER JOIN YourTable c ON b.key=c.key
WHERE c.Key is NULL
--find differences
SELECT
b.key,c.key
from YourTable c
LEFT OUTER JOIN backupserver.databasename.owner.YourTable b ON c.key=b.key
WHERE b.Key is not null
AND ( ISNULL(c.column1,-9999) != ISNULL(b.column1,-9999)
OR ISNULL(c.column2,'~') != ISNULL(b.column2,'~')
OR ISNULL(c.column2,GETDATE()) != ISNULL(b.column2,GETDATE())
)
SQL Server Management Studio for SQL Server 2008 allows you to export table data as insert statements. See http://www.kodyaz.com/articles/sql-server-script-data-with-generate-script-wizard.aspx. This approach lacks some of the flexibility of sp_generate_inserts (you cannot specify a WHERE clause to filter the rows in your table, for example) but may be more reliable since it is part of the product.