I have list of records in TIBDataSet (Embarcadero Delphi) and I need to locate and modify one record in this list. There is chance that underlying database record has been changed by other queries and operations since TIBDataSet had been opened. Therefor I would like to call RefreshSQL for this one record (to get the latest data) before making any changes and before making post. Is it possible to do so and how?
I am not concerned about state of other records and I am sure that the record under consideration will always be updated and those updates will be commited before I need to changes this record from TIBDataSet.
As far as I understand then RefreshSQL is used for automatic retrieve of changes after TIBDataSet has posted upates to database. But I need manual (explicit) retrieval of the latest state before doing updates.
Try adding a TButton to your form and add the following code to its OnClick handler:
procedure TForm1.btnRefreshClick(Sender: TObject);
begin
IBQuery1.Refresh; // or whatever your IBX dataset is called
end;
and set a breakpoint on it.
Then run your app and another one (e.g. 2nd instance of it) and change a row in the second app, and commit it back to the db.
Navigate to the changed row in your app and click btnRefresh and use the debugger to trace execution.
You'll find that TDataSet.Refresh calls its InternalRefresh which in turn calls TIBCustomDataSet.InternalRefresh. That calls inherited InternalRefresh, which does nothing, followed by TIBCustomDataSet.InternalRefreshRow. If you trace into that, you'll find that it contructs a temporary IB query to retrieve the current row from the server, which should give you what you want before making changes yourself.
So that should do what you want. The problem is, it can be thoroughly confusing trying to monitor the data in two applications because they may be in different transaction states. So you are rather dependent on other users' apps "playing the transactional game" with you, so everyone sees a consistent view of the data.
Why isn't it standard behavior for Accurev to automatically run an "Update" upon opening the program? "Update" updates a user's local sandbox with the latest files from the building/promoted area.
It seems like expected functionality that the most recent files should be synchronized first.
I'm not claiming that it should always update, but curious as to why an auto-Update wouldn't be correct.
Auto-updating could produce some very unwanted results.
Take this scenario: you're in the middle of a development task, but you've made a mistake and need to revert a file that you just modified. So you open AccuRev, but before you have a chance to "revert to most recent version", you are bombarded with 100 files that have been changed upstream including the one you want to revert. You are now forced into the position of resolving all the merge conflicts before your solution will build, including the merge of your (possibly unstable) code in progress.
Requiring the user to manually update keeps a protective 'bubble' around the developer, allowing them to commit (keep) changes within their own workspace without bringing down code changes that could destabilise the work in their sandbox. When the developer gets to a point where his code is ready to share with others, that is the appropriate time to do an update and subsequently build/retest the merged codebase before promoting.
However there is one scenario that I do believe auto-updating could be useful: after a workspace is reparented. i.e. when a developer's workspace is moved from one part of the stream hierarchy to another. Every time we reparent we have to do a little dance:
Accept the confirmation dialog that reminds us (rather verbosely) that we need to update our workspace before we can promote any changes.
Double-click the workspace to view its files.
Wait for AccuRev to do a "Pending" search, to determine whether any file changes are waiting to be committed.
And finally, perform the Update.
Instead of just giving us a confirmation dialog, it would be nice if AccuRev could just ask us if we want to Update immediately.
I guess it depends on preference. I for one wouldn't like the auto-update feature.
Imagine you have a huge project and you don't want to build it every time you start Accurev. But you also can't debug because the source files and debugging info no longer correspond.
I altered a stored procedure and unknowingly overwrote some changes that were made to it by another developer. Is there a way to undo the changes and get the old script back?
Unfortunately I do not have a backup of that database, so that option is ruled out.
The answer is YES, you can get it back, but it's not easy. All databases log every change made to it. You need to:
Shutdown the server (or at least put it into read-only mode)
Take a full back up of the server
Get a copy of all the db log files going back to before when the accident happened
Restore the back up onto another server
Using db admin tools, roll back through the log files until you "undo" the accident
Examine the restored code in the stored proc and code it back into your current version
And most importantly: GET YOUR STORED PROCEDURE CODE UNDER SOURCE CONTROL
Many people don't grok this concept: You can only make changes to a database; you can't roll back the stored proc version like you can with application code by replacing files with their previous versions. To "roll back", you must make more changes that drop/define your stored proc.
Note to nitpickers: By "roll back" I do not mean "transaction roll back". I mean you've made your changes and decide once the server is back up that the change is no good.
"Is there a way to undo the changes and get the old script back?"
Short answer: Nope.
:-(
In addition to the sound advice to either use a backup or recover from source control (and if you're doing neither of those things, you need to start), you could also consider getting SSMS Tools Pack from #MladenPrajdic. His Management Studio add-in allows you to keep a running history of all the queries you've worked on or executed, so it is very easy to go back in time and see previous versions. While that doesn't help you if someone else worked on the last known good version, if your entire team is using it, anyone can go back and see any version that was executed. You can dictate where it is saved (to your own file system, a network share, or a database), and fine-tune how often auto-save kicks in. Really priceless functionality, especially if you're lazy about backups and/or source control (though again, I stress, you should be doing these things before you touch your production server again).
You could look through the cached execution plans and try to find the one where your colleague made his changes and run the relevant parts again.
EDIT
Although Bohemian looks to have a good answer if you've got the changes in the TL, this is what I'm talking about. Review the SQL text for the plan.
SELECT cached.*,
sqltext.*
FROM sys.dm_exec_cached_plans cached
CROSS APPLY sys.dm_exec_sql_text (cached.plan_handle) AS sqltext
But as squillman points out, there is no execution plan for DDL.
You won't be able to get it back from the database side of things. Your options at this point are pretty much limited to 1) recover from backup, 2) go to source control or 3) hope that someone else has a copy still up in an editor somewhere or saved to a file.
If neither of these are an option for you, then here's the obligatory "you should take regular backups and use source control"....
I'm way late to the game on this but I did this same thing this morning and found I had forgot to save my script at some point in the past and needed to recover it. (It will be in source control after I get done fixing this!!!)
Some people mentioned restoring from a backup but no one really mentioned how easy this is if you have a back up. Moreover, you aren't locked into rolling back the production database. I think this is key and assuming you have a back up I would say this is a much better alternative to what has been voted up to the best answer.
All you have to do is take your back up and restore it to a new database. Pull out the sp you are looking for and voila, you've recovered the missing code.
Don't forget to drop the newly created database after you've recovered the missing file.
I had the same problem, and I don't have the confidence to go restoring from log files to another server. I was pretty distraught until I realised the solution was very simple...
Press Ctrl-Z over and over until I had undone my changes and the run the ALTER PROCEDURE again.
Admittedly I was pretty lucky that I still had it there to revert to but it really is the easiest fix. Probably a bit late now though.
If you have scripted the stored procedure out from management studio object explorer this will work.
Before expand and collapse the object explorer just scroll and point to the stored procedure you have opened. Script the stored procedure as create or alter to then you can get the previous version of the proc since the object explorer doesn't refreshed yet. This is always my life saver.
I have got a database of ms-sql server 2005 named mydb, which is being accessed by 7 applications from different location.
i have created its copy named mydbNew and tuned it by applying primary keys, indexes and changing queries in stored procedure.
now i wants to replace old db "mydb" from new db "mydbnew"
please tell me what is the best approach to do it. i though to do changes in web.config but all those application accessing it are not accessible to me, cant go for it.
please provide me experts opinion, so that i can do replace database in minimum time without affecting other db and all its application.
my meaning of saying replace old db by new db is that i wants to rename old db "mydb" to "mydbold" and then wants to remname my new db "mydbnew" to "mydb"
thanks
Your plan will work but it does carry a high risk, especially since I'm assuming this is a system that has users actively changing data, which means your copy won't have the same level of updated content in it unless you do a cut right before go-live. Your best bet is to migrate your changes carefully into the live system during a low traffic / maintenance period and extensively test it once your done. Prior to doing this, or the method you mentioned previously, backup everything.
All of the changes you described above can be made to an online database without the need to actually bring it down. However, some of those activities will change the way in which the data is affected by certain actions (changes to stored procs), that means that during the transition the behaviour of the system or systems may be unpredicatable and therefore you should either complete this update at a low point in day to day operations or take it down for a maintenance window.
Sql Server comes with a function to make a script file out of you database, you can also do this manually but clicking on the object you want to script and selecting the Script -> CREATE option. Depending on the amount of changes you have to make it may be worthwhile to script your whole new database (By clicking on the new database and selecting Tasks -> Generate Scripts... and selecting the items needed).
If you want to just script out the new things you need to add individually then you simply click on the object you want to script, select the Script <object> as -> then select DROP and CREATE to if you want to kill the original version (like replacing a stored proc) or select CREATE to if your adding new stuff.
Once you have all the things you want to add/update as a script your then ready to execute that against the new database. This would be the part where you backup everything. Once your happy everything is backed up and the system is in maintenance or a low traqffic period, you execute the script. There may be a few problems when you do this, you will need to fix these as quickly as possible (usually mostly just 'already exisits' errors, thats why drop and create scripts are good) and if anything goes really wrong restore your backups and try again (after figuring out what happened and how to fix it).
Make no mistake if you have a lot of changes to make this could be a long process, or it could take mere minutes, you just need to adapt if things go wrong and be sure to cover yourself with backups/extensive prayer. Good Luck!
I'm using SQL-Server 2008 with Visual Studio Database Edition.
With this setup, keeping your schema in sync is very easy. Basically, there's a 'compare schema' tool that allow me to sync the schema of two databases and/or a database schema with a source-controlled creation script folder.
However, the situation is less clear when it comes to data, which can be of three different kind :
static data referenced in the code. typical example : my users can change their setting, and their configuration is stored on the server. However, there's a system-wide default value for each setting that is used in case the user didn't override it. The table containing those default settings grows as more options are added to the program. This means that when a new feature/option is checked in, the system-wide default setting is usually created in the database as well.
static data. eg. a product list populating a dropdown list. The program doesn't rely on the existence of a specific product in the list to work. This can be for example a list of unicode-encoded products that should be deployed in production when the new "unicode version" of the program is deployed.
other data, ie everything else (logs, user accounts, user data, etc.)
It seems obvious to me that my third item shouldn't be source-controlled (of course, it should be backuped on a regular basis)
But regarding the static data, I'm wondering what to do.
Should I append the insert scripts to the creation scripts? or maybe use separate scripts?
How do I (as a developer) warn the people doing the deployment that they should execute an insert statement ?
Should I differentiate my two kind of data? (the first one being usually created by a dev, while the second one is usually created by a non-dev)
How do you manage your DB static data ?
I have explained the technique I used in my blog Version Control and Your Database. I use database metadata (in this case SQL Server extended properties) to store the deployed application version. I only have scripts that upgrade from version to version. At startup the application reads the deployed version from the database metadata (lack of metadata is interpreted as version 0, ie. nothing is yet deployed). For each version there is an application function that upgrades to the next version. Usually this function runs an internal resource T-SQL script that does the upgrade, but it can be something else, like deploying a CLR assembly in the database.
There is no script to deploy the 'current' database schema. New installments iterate trough all intermediate versions, from version 1 to current version.
There are several advantages I enjoy by this technique:
Is easy for me to test a new version. I have a backup of the previous version, I apply the upgrade script, then I can revert to the previous version, change the script, try again, until I'm happy with the result.
My application can be deployed on top of any previous version. Various clients have various deployed version. When they upgrade, my application supports upgrade from any previous version.
There is no difference between a fresh install and an upgrade, it runs the same code, so I have fewer code paths to maintain and test.
There is no difference between DML and DDL changes (your original question). they all treated the same way, as script run to change from one version to next. When I need to make a change like you describe (change a default), I actually increase the schema version even if no other DDL change occurs. So at version 5.1 the default was 'foo', in 5.2 the default is 'bar' and that is the only difference between the two versions, and the 'upgrade' step is simply an UPDATE statement (followed of course by the version metadata change, ie. sp_updateextendedproperty).
All changes are in source control, part of the application sources (T-SQL scripts mostly).
I can easily get to any previous schema version, eg. to repro a customer complaint, simply by running the upgrade sequence and stopping at the version I'm interested in.
This approach saved my skin a number of times and I'm a true believer now. There is only one disadvantage: there is no obvious place to look in source to find 'what is the current form of procedure foo?'. Because the latest version of foo might have been upgraded 2 or 3 versions ago and it wasn't changed since, I need to look at the upgrade script for that version. I usually resort to just looking into the database and see what's in there, rather than searching through the upgrade scripts.
One final note: this is actually not my invention. This is modeled exactly after how SQL Server itself upgrades the database metadata (mssqlsystemresource).
If you are changing the static data (adding a new item to the table that is used to generate a drop-down list) then the insert should be in source control and deployed with the rest of the code. This is especially true if the insert is needed for the rest of the code to work. Otherwise, this step may be forgotten when the code is deployed and not so nice things happen.
If static data comes from another source (such as an import of the current airport codes in the US), then you may simply need to run an already documented import process. The import process itself should be in source control (we do this with all our SSIS packages), but the data need not be.
Here at Red Gate we recently added a feature to SQL Data Compare allowing static data to be stored as DML (one .sql file for each table) alongside the schema DDL that is currently supported by SQL Compare.
To understand how this works, here is a diagram that explains how it works.
The idea is that when you want to push changes to your target server, you do a comparison using the scripts as the source data source, which generates the necessary DML synchronization script to update the target. This means you don't have to assume that the target is being recreated from scratch each time. In time we hope to support static data in our upcoming SQL Source Control tool.
David Atkinson, Product Manager, Red Gate Software
I have come across this when developing CMS systems.
I went with appending the static data (the stuff referenced in the code) to the database creation scripts, then a separate script to add in any 'initialisation data' (like countries, initial product population etc).
For the first two steps, you could consider using an intermediate format (ie XML) for the data, then using a home grown tool, or something like CodeSmith to generate the SQL, and possible source files as well, if (for example) you have lookup tables which relate to enumerations used in the code - this helps enforce consistency.
This has another benefit that if the schema changes, in many cases you don't have to regenerate all your INSERT statements - you just change the tool.
I really like your distinction of the three types of data.
I agree for the third.
In our application, we try to avoid putting in the database the first, because it is duplicated (as it has to be in the code, the database is a duplicate). A secondary benefice is that we need no join or query to get access to that value from the code, so this speed things up.
If there is additional information that we would like to have in the database, for example if it can be changed per customer site, we separate the two. Other tables can still reference that data (either by index ex: 0, 1, 2, 3 or by code ex: EMPTY, SIMPLE, DOUBLE, ALL).
For the second, the scripts should be in source-control. We separate them from the structure (I think they typically are replaced as time goes, while the structures keeps adding deltas).
How do I (as a developer) warn the people doing the deployment that they should execute an insert statement ?
We have a complete procedure for that, and a readme coming with each release, with scripts and so on...
First off, I have never used Visual Studio Database Edition. You are blessed (or cursed) with whatever tools this utility gives you. Hopefully that includes a lot of flexibility.
I don't know that I'd make that big a difference between your type 1 and type 2 static data. Both are sets of data that are defined once and then never updated, barring subsequent releases and updates, right? In which case the main difference is in how or why the data is as it is, and not so much in how it is stored or initialized. (Unless the data is environment-specific, as in "A" for development, "B" for Production. This would be "type 4" data, and I shall cheerfully ignore it in this post, because I've solved it useing SQLCMD variables and they give me a headache.)
First, I would make a script to create all the tables in the database--preferably only one script, otherwise you can have a LOT of scripts lying about (and find-and-replace when renaming columns becomes very awkward). Then, I would make a script to populate the static data in these tables. This script could be appended to the end of the table script, or made it's own script, or even made one script per table, a good idea if you have hundreds or thousands of rows to load. (Some folks make a csv file and then issue a BULK INSERT on it, but I'd avoid that is it just gives you two files and a complex process [configuring drive mappings on deployment] to manage.)
The key thing to remember is that data (as stored in databases) can and will change over time. Rarely (if ever!) will you have the luxury of deleting your Production database and replacing it with a fresh, shiny, new one devoid of all that crufty data from the past umpteen years. Databases are all about changes over time, and that's where scripts come into their own. You start with the scripts to create the database, and then over time you add scripts that modify the database as changes come along -- and this applies to your static data (of any type) as well.
(Ultimately, my methodology is analogous to accounting: you have accounts, and as changes come in you adjust the accounts with journal entries. If you find you made a mistake, you never go back and modify your entries, you just make a subsequent entries to reverse and fix them. It's only an analogy, but the logic is sound.)
The solution I use is to have create and change scripts in source control, coupled with version information stored in the database.
Then, I have an install wizard that can detect whether it needs to create or update the db - the update process is managed by picking appropriate scripts based on the stored version information in the database.
See this thread's answer. Static data from your first two points should be in source control, IMHO.
Edit: *new
all-in-one or a separate script? it does not really matter as long as you (dev team) agree with your deployment team. I prefer to separate files, but I still can always create all-in-one.sql from those in the proper order [Logins, Roles, Users; Tables; Views; Stored Procedures; UDFs; Static Data; (Audit Tables, Audit Triggers)]
how do you make sure they execute it: well, make it another step in your application/database deployment documentation. If you roll out application which really needs specific (new) static data in the database, then you might want to perform a DB version check in your application. and you update the DB_VERSION to your new release number as part of that script. Then your application on a start-up should check it and report an error if the new DB version is required.
dev and non-dev static data: I have never seen this case actually. More often there is real static data, which you might call "dev", which is major configuration, ISO static data etc. The other type is default lookup data, which is there for users to start with, but they might add more. The mechanism to INSERT these data might be different, because you need to ensure you do not destoy (power-)user-created data.