I have just taken over a project for a client and the database schema is in a total mess. I would like to rename a load of fields make it a relationship database.
But doing this will be a painstaking process as they have an API running of it also. So the idea would be to create a new database and start re-writing the code to use this instead. But I need a way to keep these tables in sync during this process.
Would you agree that I should use MYSQL EVENT's to keep updating the new table on Inserts / updates & deletes??
Or can you suggest a better way??
Hope you can advise !!
thanks for any input I get
I had the same problem in my project. I did the same thing like you - writing the whole database new. We developed the new database and the fitting code and after finishing that work we made a migration script (small application) which did the migration from old to new database.
Hope this gives you some ideas...
I had the same problem as well, and went by the way of duplicating data at the point of user input (basically saved to both databases at once, since the original schema lacked all the required information). After several months of development the customer realized that he is going to move to a completely new database and considered it too risky (and I agree with him).
Thus, I would advice to utter clearly to your customer that you are going to implement a new database instead of iterative refactoring of the current one.
Related
I am using mysql database for my site.
I have create one site using codeigniter php framework and mysql.
Now after few months I have updated that site and also the database.
I have added some new columns to my database table not deleted or alert any previous one.
Now I want to update my site but don't want to lose data that I already have right now.
Is there anyway I can update database without losing the data present in it.
If your database is created/updated automatically by some modeling tool, I think the best you way you should do is to understand those changes and write the "alter table" statements yourself and run it in your deployment.
As user1281385 pointed in answer https://stackoverflow.com/a/22012478/1033539 , there may be some tool that can help you generate those statements.
SQLyog has a great feature called "Schema Synchronization tool" which will do it
they also have a blog comparing other methods of doing it
http://blog.webyog.com/2012/10/16/so-how-do-you-sync-your-database-schema/
Im sure other similar tools can do it also
Edit:
Mysql Workbench also has this feature
http://www.mysql.com/products/workbench/features.html
So I have an old website which was coded over an extended period of time but has been inactive for 3 or so years. I have the full PHP source to the site, but the problem is I do not have a backup of the database any longer. I'm wondering what the best solution to recreating the database would be? It is a large site so manually going through each PHP file and trying to keep track of which tables are referenced is no small task. I've tried googling for the answer but have had no luck. Does anyone know of any tools that are available to help extract this information from the PHP and at least give me the basis of a database skeleton? Otherwise, has anyone ever had to do this? Any tips to help me along and possibly speed up the process? It is a mySQL database I'm trying to use.
The way I would do it:
Write a subset of SQLi or whatever interface was used to access the DB to intercept all DB accesses.
Replace all DB accesses with the dummy version of yours.
The basic idea is to emulate the DB so that the PHP code runs long enough to activate the various DB accesses, which in turn will allow you to analyze the way the DB is built and used.
From within these dummy functions:
print the SQL code used
regenerate just enough dummy results to let the rest of the code run, based on the tables and fields mentioned in the query parameters and the PHP code that retrieves them (you won't learn much from a SELECT *, but you can see what fields the PHP code expects to get from it)
once you have understood enough of the DB structure, recreate the tables and let the original code work on them little by little
have the previous designer flogged to death for not having provided a way to recreate the DB programatically
There are currently two answers based on the information you provided.
1) you can't do this
PHP is a typeless language. you could check you sql statements for finding field and table names. but it will not complete. if there is a select * from table, you can't see the fields. so you need to check there php accesses the fields. maybe by name or by index. you could be happy if this is done by name, because you can extract the name of the fields. finally the data types will missing. also missing: where are is an index on, what are primary keys, constrains etc.
2) easy, yes you can!
because your php is using a modern framework with contains a orm. this created the database for you. a meta information are included in the php classes/design.
just check the manual how to recreate the database.
I'm working on a software solution which was written using PHP Symfony with mysql database. When we do upgrades to the existing product what we use now is copping the existing database to a new database and do the upgrade standing on the new database. But the current method of asking the user to copy the existing database does not seem to be the professional way to do an upgrade.
Is there any standard way of doing that automatically and preserve the consistency of the old database? Please help me on this issue. Thanks in advance.
You could create a copy of the tables with a different table prefix (like updateAttempt_) and then if everything goes well delete the old ones and rename the new ones to the old ones.
Although, If you're doing this to make sure the data isn't corrupted in the event something goes wrong.. isn't that what TRANSACTIONS are for?
Since RedBean creates all columns by itself what would happen if I don't need a field any more. Is there an easy way to remove it without deleting the table and lose all data?
Can this be solved automaticaly or how would RedBean react if I delete the column manually?
Delete the table column in the usual way from your MySQL client (say, phpMyAdmin or SQLYog) or from the MySQL console.
RedBean can't get confused by this "external meddling" that you're worried about, because it runs on each PHP script execution and, to the best of my knowledge, carries no state across invocations. It's really just an abstraction over data storage.
Interestingly, the RedBean Wiki doesn't appear to talk about this sort of thing at all.
I am working on a web based application using Zend framework.
I am looking for a way to keep history of updates made to a bunch of columns.
Use-case:
User can add an item with 5 properties. The user is allowed to update the 5 properties. I need to track all the updates he makes to those 5 properties.
On way I thought of was adding a new table named log which stores the old value, new value, column name, itemID and timestamp.
What is the best way to do this? Are there any existing methods/options/examples ?
Thanks,
What you're probably looking for is an audit log. You can create one using Triggers on your MySQL database.
An example of how to do this is here: http://ronaldbradford.com/blog/auditing-your-mysql-data-2008-07-15/
In your comment below you added that the database is not 'fixed'. In that case, you'd have to replicate any alters to the table so that they are applied to the audit table in such a way that any newly added columns are added to the log as well.
You can consider logging this in your application (as your tags chosen for this question seem to suggestion) - but keep in mind that this means there can be situations where your log does not provide the complete answer. Triggers, stored procedures and any manual interventions in the database will not be logged... so be careful if you choose to go down that path.
Triggers are the most common way to do auditing and the only really reliable way to capture what was done whether done from the user interface or elsewhere. They do vary by database in how they would be written though. If you know the possible types of database backends you will support, you could write separate triggers for each.
If you must handle this without triggers, then your best bet is to have a process that writes to the audit table as well as makes the update change. It might be complex enough to warrant a stored proc called by the Zend framework rather than relying on the framework itself to do. (I'm not familair with Zend so I don't know if this is something that could be set up, I know a stored proc could handle this.)
Here is a better one..
See Pop On the Audit Trail
I just created a new table called it Comp_Hist_Log and then defined the old data in the
BEFORE UPDATE hook
$oldData = $array('fieldname1', 'fieldname2')
Then at the AFTER_UPDATE hook in my database gui hook file.. I added this code
sql("INSERT INTO Comp_Hist_Log (Com_Rec_Id, old_data, new_data, ChangedDate, ChangedBy)
VALUES('{$data['Record_Id']}', '{$oldData}', '{$messageData}', '{$data['LastUpdated']}', '{$memberInfo['username']}')", $eo);
return TRUE;
Hope it helps.. it does work.