Handling database migrations when using Entity Framework - sql

We are building an app in C# which uses Entity Framework with SQL Server 2008. We design the model using the designer in Visual Studio and auto-generate entities from this.
We're working on version 1.0. When we release 2.0, we'll need to make changes to the model and underlying database structure. I guess we need what's called "database migrations".
Traditionally, I've had a table in the database called something like 'version'. Whenever I've created a new version of my software, I've created database upgrade scripts containing ALTER TABLE statements. My software has checked the version table and run the upgrade scripts needed to upgrade the database to the 'software version'.
Is there some better way of handling this? It would be nice if I didn't have to write the alter table-scripts myself and write my own software to upgrade the database structure.

What I used to do when I did model first, is I pointed my model to a database that was purely for schema (so I had a myapp database, which was where my app ran, but my EF4 model was outputted to a myapp_schema database). When the myapp_schema was updated, I used Db Source Tools to generate the update scripts and make the myapp's database schema be the same as myapp_schema.

Chech this post out. It's about CTP4 of EF4, but it thing this is what you need.
http://blogs.msdn.com/b/efdesign/archive/2010/10/22/code-first-database-evolution-aka-migrations.aspx
Unforunately this isn't yet available. CTP5 was released a few days ago and as far as I know this is not yet included.

Related

ASP.NET MVC 4 Code First Solution Setup Using SQL Server 2012

I am planning to create a web application using ASP.NET MVC4 using the code first approach.
I am using Visual Studio 2012 and I have SQL Server 2012. What I would like to do is setup the solution in a way that I can use SQL Server instead of the default being SQL Express or localDB. I would like to have the solution regenerate the database if any changes are made to the models and seed the database with some test data when that occurs.
I have gone through a bunch of tutorials and they all seem to be using the SQL Express or LocalDB database. I was able to get the solution to generate the database on SQL Server the first time it was run, but after I make changes to the model such as alter the schema name from 'dbo' to lets say 'test' or change the table name, it doesn't seem to pick up those changes.
Can anyone give me some insight on how I might be able to accomplish this?
Thanks
All you need to do is have your connection string in the web.config pointing to your SQL server for it to use that server instance.
As for having it update on model change, have a look into DropCreateDatabaseIfModelChanges.
In your Global.asax you can set your database initializer like this
Database.SetInitializer(new DropCreateDatabaseIfModelChanges<DbContext>());
You will need a using statement too
using System.Data.Entity;
There is a free video guide to MVC4 by Scott Allen which can give you more info on Migrations and Code First (which is what you are asking about). The 4th section of the video guide has a 13 minute segment on Data Migrations which is a full walk through. If you can spare the time, watch that for a full detailed guide.http://www.asp.net/mvc/videos/pluralsight-building-applications-with-aspnet-mvc-4
I might point out this is only useful in development and there is no way to make it work for production as you would lose your data. If you need something that is suitable for a production environment look into SSDT (SQL Server Data Tools). You can manage your database as a SQL project in your solution and deploy updates using a DACPAC file. The file manages all the updates in production and can be set to protect against data loss. You can change and deploy your Db from your project and still use EF with database first and EF models etc. All you do is make your changes in the Db project and hit debug to update your test Db. When publishing you can choose to export the DACPAC for updating live.

How to automate deployment of entity model changes to database?

Currently I use Visual Studio Database Project, so I can deploy changes to database with one click and keep data in database.
Now I want to be able to create model in Entity Framework and deploy with one click.
So I got sql script to create database from Entity Framework. I can run this script to create database, but I want to keep my data in database.
Is there any way to do that ? Any tool that will do that ? Should I generate it on my own with T4 ?
I use CI so I need to be able to deploy often. I want something similar to Visual Studio Database Project deployment, but with Entity Framework generated database.
Liquibase is a database change management tool. It's implemented in Java but a command-line version is available to control your database upgrades (.NET version is under development).
If you need some modelling tool support then
Power architect can be used with liquibase.
The problems associated with managing database schema upgrades are subtle. For some background reading I would recommend:
Evolutionary Database Design
Get your database under version control
Update
Create a file called liquibase.properties to hold the database details:
url=jdbc:sqlserver://localhost:1433;databaseName=test
username=myuser
password=mypass
driver=com.microsoft.sqlserver.jdbc.SQLServerDriver
classpath=C:\\Program Files\\Microsoft SQL Server 2005 JDBC Driver\\sqljdbc_1.2\\enu\\sqljdbc.jar
changeLogFile=database-changelog.xml
When using liquibase against an existing database you can run the following commands:
liquibase generateChangeLog
liquibase changelogSync
The first command will create an XML file called database-changelog.xml containing the extracted data model.
The second command is optional, but useful if you want to apply new changes to the current database. It marks the extracted changesets as already executed in the database.
Now that you have a starting point, you can proceed to add new changesets to the database-changelog.xml file. To apply these new changes just run the following command:
liquibase update
This is the same command that you use for brand new databases. During an update operation liquibase will compare the changesets in the XML file to the changesets already applied to the target database.
For more advanced usecases I suggest reading the liquibase documentation and the following answer may also help:
comparing databases and genrating sql script using liquibase
To be able to generate Visual Studio Database Project from Entity Framework Model You need to install Entity Designer Database Generation Power Pack.
You need to add Database Project to Your solution and then create edmx model with the same name. Then right click on edmx workspace and select Generate Database from Model and from generation menu Sync Database Project.
You can then deploy this Sql project from Visual Studio to Sql Server.

Managing a subset of the database in a SQL Server 2008 DB Project

I'm new to using SQL Server 2008 DB Project's in VS 2010. I found a good intro to setting them up. It's nice how they create Tables, Stored Proc's etc as objects. But is it also a limitation?
I want to use this project to manage 1 stored procedure (for learning). I do not want to import the entire database because 90% of the database is stuff we do not manage.
I created a new project without doing the import process. I then added a new stored procedure. Now I am having difficulty getting the thing to build. I'm getting various errors saying that I have unresolved references to objects.
How can I add a new stored procedure..build it and deploy it to the database? Is it possible with this kind of SQL project or do I need to drop back to the old, simple type of SQL projects that VS 2008 and below used?
Update
According to another post, support for the Database Project type is gone. Support for my situation appears to have been erased.
UPDATE 2 3/21/2012
I installed MSSCCI which allows me to use SSMS directly with TFS 2010. I no longer needed and found the setup process to be unmanageable for a large database SQL 2008 project. Especially when you only manage a small % of the DB.
You can Partition a Database Project by Using Partial Projects. This allows the database project to know the entire schema of the database, at the same time, you need not maintain the entire schema. You can work with the subset of the database that's under active development, for instance (or the subset which is your responsibility), yet the project knows the entire schema. This permits it to create change scripts at deployment time, by comparing the schema in the project with the schema in the target database.
You must import all schema objects referenced by your new stored procedure. But this can become a large task because every referenced object need all it's references too.
More trouble with linked server objects.

Best way to version control T-SQL? [duplicate]

This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Stored procedures/DB schema in source control
What's the best way to version control my tables, views, sprocs, etc? Preferably automated or at least semi-automated :)
Thanks
I asked this one yesterday and got some nice responses:
Stored procedures/DB schema in source control
The articles from K Scott Allen say it all:
http://odetocode.com/Blogs/scott/archive/2008/01/31/11710.aspx
Write migration scripts for all db changes and keep them in a repository. Enforce a policy of making all changes to the db only by running a script; that way there is a record of what has been done, and a way to revert it. Investigate whether there's a migrations framework available for your favorite language/db combination.
I use Visual Studio 2008 Pro create Database projects (Other project types -> Database). We already use SVN as a code repository, so a project with a bunch of .sql files representing your stored procedures is just another thing to put in the repository - you can see diffs/history etc. This works the same with VSS or any other repository you use.
The nice thing about Database projects is that your project will remember your connection string, and all you have to do is right click on a .sql file (or select all of them at once!) and select run to update it in the db. This makes it easy to update your .sql files from the repository and run them all to update all your stored procedures, verifying your database is updated in seconds.
You can also select create a LINQ project (Visual C# -> Database) and store all your LINQ code in your repository.
Hope that helps!
If you were super lazy you could use the SMO (SQL Server Management Objects) or if using SQL Server prior to 2005 the DMO (distributed managmeent objects) to script out all tables/views/stored procedures daily and then compare the script to the script in source control and if there are any changes check the new version in. You won't be able to necessarily have as pretty of a script as if you just created all db changes in scripts, but at least you can recreate all tables/stored procedures/views. For example, in my table creation scripts there are often comments.
Here is an article to get you started on scripting: http://www.sqlteam.com/article/scripting-database-objects-using-smo-updated.
Again, this is mainly if you are too lazy to bother with version control and it won't help if you change something twice in one day. Also any data migration scripts still have to be saved and checked in because this won't pick up ad hoc SQL, only database objects.
I have written a DDL trigger which logs all the changes done to the definition of SQL objects (triggers, tables, SP, view etc). I could very well invoke extended SP from the trigger and store the details in another Database and use that as repository.
But if your team is really disciplined any source control should do the trick. The trigger is used as an audit mechanism and it's ideal for teams which are geographically scattered.
Try Randolph, One of the best SQL Version control tools I know.
I'm using Visual Studio Database edition which can export the schema from SQL Server in to a Visual Studio project. This is then stored in Source Control and can be deployed where ever needed. The VS Database project is just a bunch of scripts though and it's a clunky way of working.
A more robust method would be to use a database migration framework and if you're working with .Net check out this blog post for a good description http://flux88.com/NETDatabaseMigrationToolRoundup.aspx.
Update
As mentioned in the comments, this page is no more. So here is the last known snapshot from wayback machine http://web.archive.org/web/20080828232742/http://flux88.com/NETDatabaseMigrationToolRoundup.aspx

Is there a version control system for database structure changes?

I often run into the following problem.
I work on some changes to a project that require new tables or columns in the database. I make the database modifications and continue my work. Usually, I remember to write down the changes so that they can be replicated on the live system. However, I don't always remember what I've changed and I don't always remember to write it down.
So, I make a push to the live system and get a big, obvious error that there is no NewColumnX, ugh.
Regardless of the fact that this may not be the best practice for this situation, is there a version control system for databases? I don't care about the specific database technology. I just want to know if one exists. If it happens to work with MS SQL Server, then great.
In Ruby on Rails, there's a concept of a migration -- a quick script to change the database.
You generate a migration file, which has rules to increase the db version (such as adding a column) and rules to downgrade the version (such as removing a column). Each migration is numbered, and a table keeps track of your current db version.
To migrate up, you run a command called "db:migrate" which looks at your version and applies the needed scripts. You can migrate down in a similar way.
The migration scripts themselves are kept in a version control system -- whenever you change the database you check in a new script, and any developer can apply it to bring their local db to the latest version.
I'm a bit old-school, in that I use source files for creating the database. There are actually 2 files - project-database.sql and project-updates.sql - the first for the schema and persistant data, and the second for modifications. Of course, both are under source control.
When the database changes, I first update the main schema in project-database.sql, then copy the relevant info to the project-updates.sql, for instance ALTER TABLE statements.
I can then apply the updates to the development database, test, iterate until done well.
Then, check in files, test again, and apply to production.
Also, I usually have a table in the db - Config - such as:
SQL
CREATE TABLE Config
(
cfg_tag VARCHAR(50),
cfg_value VARCHAR(100)
);
INSERT INTO Config(cfg_tag, cfg_value) VALUES
( 'db_version', '$Revision: $'),
( 'db_revision', '$Revision: $');
Then, I add the following to the update section:
UPDATE Config SET cfg_value='$Revision: $' WHERE cfg_tag='db_revision';
The db_version only gets changed when the database is recreated, and the db_revision gives me an indication how far the db is off the baseline.
I could keep the updates in their own separate files, but I chose to mash them all together and use cut&paste to extract relevant sections. A bit more housekeeping is in order, i.e., remove ':' from $Revision 1.1 $ to freeze them.
MyBatis (formerly iBatis) has a schema migration, tool for use on the command line. It is written in java though can be used with any project.
To achieve a good database change management practice, we need to identify a few key goals.
Thus, the MyBatis Schema Migration System (or MyBatis Migrations for short) seeks to:
Work with any database, new or existing
Leverage the source control system (e.g. Subversion)
Enable concurrent developers or teams to work independently
Allow conflicts very visible and easily manageable
Allow for forward and backward migration (evolve, devolve respectively)
Make the current status of the database easily accessible and comprehensible
Enable migrations despite access privileges or bureaucracy
Work with any methodology
Encourages good, consistent practices
Redgate has a product called SQL Source Control. It integrates with TFS, SVN, SourceGear Vault, Vault Pro, Mercurial, Perforce, and Git.
I highly recommend SQL delta. I just use it to generate the diff scripts when i'm done coding my feature and check those scripts into my source control tool (Mercurial :))
They have both an SQL server & Oracle version.
I wonder that no one mentioned the open source tool liquibase which is Java based and should work for nearly every database which supports jdbc. Compared to rails it uses xml instead ruby to perform the schema changes. Although I dislike xml for domain specific languages the very cool advantage of xml is that liquibase knows how to roll back certain operations like
<createTable tableName="USER">
<column name="firstname" type="varchar(255)"/>
</createTable>
So you don't need to handle this of your own
Pure sql statements or data imports are also supported.
Most database engines should support dumping your database into a file. I know MySQL does, anyway. This will just be a text file, so you could submit that to Subversion, or whatever you use. It'd be easy to run a diff on the files too.
If you're using SQL Server it would be hard to beat Data Dude (aka the Database Edition of Visual Studio). Once you get the hang of it, doing a schema compare between your source controlled version of the database and the version in production is a breeze. And with a click you can generate your diff DDL.
There's an instructional video on MSDN that's very helpful.
I know about DBMS_METADATA and Toad, but if someone could come up with a Data Dude for Oracle then life would be really sweet.
Have your initial create table statements in version controller, then add alter table statements, but never edit files, just more alter files ideally named sequentially, or even as a "change set", so you can find all the changes for a particular deployment.
The hardiest part that I can see, is tracking dependencies, eg, for a particular deployment table B might need to be updated before table A.
For Oracle, I use Toad, which can dump a schema to a number of discrete files (e.g., one file per table). I have some scripts that manage this collection in Perforce, but I think it should be easily doable in just about any revision control system.
Take a look at the oracle package DBMS_METADATA.
In particular, the following methods are particularly useful:
DBMS_METADATA.GET_DDL
DBMS_METADATA.SET_TRANSFORM_PARAM
DBMS_METADATA.GET_GRANTED_DDL
Once you are familiar with how they work (pretty self explanatory) you can write a simple script to dump the results of those methods into text files that can be put under source control. Good luck!
Not sure if there is something this simple for MSSQL.
I write my db release scripts in parallel with coding, and keep the release scripts in a project specific section in SS. If I make a change to the code that requires a db change, then I update the release script at the same time.
Prior to release, I run the release script on a clean dev db (copied structure wise from production) and do my final testing on it.
I've done this off and on for years -- managing (or trying to manage) schema versions. The best approaches depend on the tools you have. If you can get the Quest Software tool "Schema Manager" you'll be in good shape. Oracle has its own, inferior tool that is also called "Schema Manager" (confusing much?) that I don't recommend.
Without an automated tool (see other comments here about Data Dude) then you'll be using scripts and DDL files directly. Pick an approach, document it, and follow it rigorously. I like having the ability to re-create the database at any given moment, so I prefer to have a full DDL export of the entire database (if I'm the DBA), or of the developer schema (if I'm in product-development mode).
PLSQL Developer, a tool from All Arround Automations, has a plugin for repositories that works OK ( but not great) with Visual Source Safe.
From the web:
The Version Control Plug-In provides a tight integration between the PL/SQL Developer IDE >>and any Version Control System that supports the Microsoft SCC Interface Specification. >>This includes most popular Version Control Systems such as Microsoft Visual SourceSafe, >>Merant PVCS and MKS Source Integrity.
http://www.allroundautomations.com/plsvcs.html
ER Studio allows you to reverse your database schema into the tool and you can then compare it to live databases.
Example: Reverse your development schema into ER Studio -- compare it to production and it will list all of the differences. It can script the changes or just push them through automatically.
Once you have a schema in ER Studio, you can either save the creation script or save it as a proprietary binary and save it in version control. If you ever want to go back to a past version of the scheme, just check it out and push it to your db platform.
There's a PHP5 "database migration framework" called Ruckusing. I haven't used it, but the examples show the idea, if you use the language to create the database as and when needed, you only have to track source files.
We've used MS Team System Database Edition with pretty good success. It integrates with TFS version control and Visual Studio more-or-less seamlessly and allows us to manages stored procs, views, etc., easily. Conflict resolution can be a pain, but version history is complete once it's done. Thereafter, migrations to QA and production are extremely simple.
It's fair to say that it's a version 1.0 product, though, and is not without a few issues.
You can use Microsoft SQL Server Data Tools in visual studio to generate scripts for database objects as part of a SQL Server Project. You can then add the scripts to source control using the source control integration that is built into visual studio. Also, SQL Server Projects allow you verify the database objects using a compiler and generate deployment scripts to update an existing database or create a new one.
In the absence of a VCS for table changes I've been logging them in a wiki. At least then I can see when and why it was changed. It's far from perfect as not everyone is doing it and we have multiple product versions in use, but better than nothing.
I'd recommend one of two approaches. First, invest in PowerDesigner from Sybase. Enterprise Edition. It allows you to design Physical datamodels, and a whole lot more. But it comes with a repository that allows you to check in your models. Each new check in can be a new version, it can compare any version to any other version and even to what is in your database at that time. It will then present a list of every difference and ask which should be migrated… and then it builds the script to do it. It’s not cheap but it’s a bargain at twice the price and it’s ROI is about 6 months.
The other idea is to turn on DDL auditing (works in Oracle). This will create a table with every change you make. If you query the changes from the timestamp you last moved your database changes to prod to right now, you’ll have an ordered list of everything you’ve done. A few where clauses to eliminate zero-sum changes like create table foo; followed by drop table foo; and you can EASILY build a mod script. Why keep the changes in a wiki, that’s double the work. Let the database track them for you.
Schema Compare for Oracle is a tool specifically designed to migrate changes from our Oracle database to another. Please visit the URL below for the download link, where you will be able to use the software for a fully functional trial.
http://www.red-gate.com/Products/schema_compare_for_oracle/index.htm
Two book recommendations: "Refactoring Databases" by Ambler and Sadalage and "Agile Database Techniques" by Ambler.
Someone mentioned Rails Migrations. I think they work great, even outside of Rails applications. I used them on an ASP application with SQL Server which we were in the process of moving to Rails. You check the migration scripts themselves into the VCS.
Here's a post by Pragmatic Dave Thomas on the subject.