I would like to have your opinions regarding best practices to adopt in SQL scripting to install a Data Base.
PROBLEM A)
In my script I have several Batches to create Tables.
Tables have many Foreign Keys to each others, at the moment I must arranges batches in the right order to avoid conflict with FK Tables.
I would like to know if could be a good practice create Tables and all columns without FK first, and at the end of the script ALTER such tables adding FK.
PROBLEM B)
My script should be use to create different DB on different Servers.
Data Base could have different name on every installation.
Now in my script I create a Database using:
CREATE DATABASE NameX
and:
USE NameX
to use it.
Because I would need update manually the script for every installation. I was thinking would be great to have a CENTRALIZED way for naming the Data Base inside a the script.
In this way changing a simple variable would create the Data Base with my name and all USE statements.
I tried to use LOCAL VARIABLES, but without success because after GO statements they go out of scope.
I do not have any experience in using sqlcmd and variables there.
Any idea how to solve it inside my script?
PS: I use MS SQL 2008 and I will load my script in MS SMS
Thanks guys for your help, this community is great :-)
avoid using "USE DATABASE"
separate the database creating script and data object creating scripts
use some code (Setup, Deploy) to execute creating database script by replacing #database_name with real name
alternative:
use some replacement tool to prepare scripts before deploy (it just replace your ###database_name### with real name)
use bat file to prepare scripts
alternative
use Database Project in the Visual Studio. VS can generate some variables that setup projects can change in the deploy process..
Normally one starts with scripting all the tables, followed by the FK scripts, index scripts and the rest. This is normal practice, as you can't add relationships to tables that are not there...
As for your second problem - there is no way I am aware of for centralizing this. Your best option is a global search/replace of the database name on open files in SSMS.
Related
I would like know the best practise how to resolve this problem.
I have many sql scripts for procedures, function, etc. (Every object has stand alone script).
In the first lines I have this code:
USE MyDatabase
GO
This code is necessary for direct running.
I Also have init.bat file where I call every script.
In bat file are some properties and one of them is server name.
I can create simply all object to different servers.
But I would like create all objects on same server to another database.
I Do not want copy all files with different USE database code.
Is there any way how can I do it.
I thought about SYNONYM of database, but this is impossible.
Do you have any advice?
Thank you
David
I have never really seen any questions (with answers) as general as this, so I'm hoping to get some useful feedback. The reason I'm asking is because I've done all of this before and I have my own ways, but sometimes I feel it's not the best practice.
Let's take for example that I can't afford better db modeling tools and I only have sql server and ms sql server management studio. What I do is:
I design with mssms, all of the entities in my db (tables, primary keys, foreign keys, indexes, etc)
then I just generate the schema script using 'Generate Scripts...' command in mssms. The script that's generated is rather large (using sql server express 2012) and seems like it's not organized for maintenance very well.
Example: after all the table creation scripts are setup, there's a bunch of ALTER TABLE commands to add all the constraints. This kind of thing seems like it would be better in the table creation script section, maybe not. Also, for upgrade-ability, I normally add for each table creation section, 'IF NOT EXISTS', so that it doesn't throw an error when I need to re-run the sql script when the db is updated with new tables, columns, etc.
Then for versioning, I generally have a separate script that I run to add the schema version in a VERSION table in the db itself (with just one row).
This allows me to do incremental upgrades when I run the script by adding 'if new-version > current-version' sort of thing.
It seems to have worked out for me in the past, but it just seems kind of, I don't know, not very sophisticated. Can a sql expert shed some light on this subject? It's something we all do for every data driven web app we create, over and over again. I'd like to see how other developers do it.
To recap,
how do you go about designing your db model and generate scripts (do you do it with a design tool, write from scratch, etc?),
how to you manage incremental db changes over time?
How do you version control your database?
SQL Server Data Tools is ideal for this. It has all the design features you require and configurable scripting. It will also diff two databases and generate the change script for you. Oh - and it's free!
I have quite old application with current database (on MSSQL but it does not matter). I scripted it completely with all required static data. Now I want to introduce DB change only via update scripts. So each function, each SP will be placed in stand-alone file and all schema update scripts will be stored in files named like 'SomeProduct01_0001' what means that this script belongs to product SomeProduct, sprint 1 and it is first schema update script.
I know that each script must be absolutely re-runnable, but anyway I want to have functionality to combine these scripts into one based on DB version (stored in DB table).
What common best practices there is to handle bunches of update scripts?
What is better - implement version anylyzis in collector
(bat or exe file) or add some SQL header to each file? From other point of view I am already have version - it will consist of sprint identifier and script identifier, not sure that it is ok to duplicate this information in script header.
How to skip file content if user tries to apply it to newer database but keep
availability combine this script with any other to perform updates
of other old database?
How to avoid database conflicts if combined scripts operates columns/table which still does not exists in database but will be created byt this script (for example, in line 10 table created and in line 60 it is used in trigger or constraint, as I know script will not be validated)? Maybe wrap in EXEC('') entire script? What I need to escape besides sigle quote characters?
UPD: As David Tanzer asnwered it is better to use ready solutions for DB migrations, so it may be best solution for cases like mine. It was not and answer exactly for my question, but it is suitable for new solutions.
You don't have to implement this yourself, there are tools that do it. Take a look at dbmaintain, it provides almost exactly the functionality you described:
http://www.dbmaintain.org/overview.html
I know of and have worked with several teams who use it to manage their database schemas in all their environments: Development, Testing, Staging and Production.
http://flywaydb.org/ seems to be another tool to do this, and it has even more features. They even have a comparison of multiple tools on their homepage (including dbmaintain)
I was wondering what are the best practices in order to write SQL scripts to set up databases for production and/or development, for instance:
Should I include the CREATE DATABASE statement?
Should I create users for the database in the same script?
Is correct to disable FK check before executing the body of the script?
May I include the hole script in a transaction?
Is better to generate 1 script per database than one script for all of them?
Thanks!
The problem with your question is is hard to answer as it depends on the way the scripts are used in what you are trying to achieve. you also don't say which DB server you are using as there are tools provided which can make some tasks easier.
Taking your points in order, here are some suggestions, which will probably be very different to everyone elses :)
Should I include the CREATE DATABASE
statement?
What alternative are you thinking of using? If your question is should you put the CREATE DATABASE statement in the same script as the table creation it depends. When developing DB I use a separate create DB script as I have a script to drop all objects and so I don't need to create the database again.
Should I create users for the database in the same script?
I wouldn't, simply because the users may well change but your schema has not. Might as well manage those changes in a smaller script.
Is correct to disable FK check before executing the body of the script?
If you are importing the data in an attempt to recover the database then you may well have to if you are using auto increment IDs and want to keep the same values. Also you may end up importing the tables "out of order" an not want checks performed.
May I include the whole script in a transaction?
Yes, you can, but again it depends on the type of script you are running. If you are importing data after rebuilding a db then the whole import should work or fail. However, your transaction file is going to be huge during the import.
Is better to generate 1 script per database than one script for all of them?
Again, for maintenance purposes it's probably better to keep them separate.
This probably depends what kind of database and how it is used and deployed. I am developing a n-tier standard application that is deployed at many different customer sites.
I do not add a CREATE DATABASE statement in the script. Creating the the database is a part of the installation script which allows the user to choose server, database name and collation
I have no knowledge about the users at my customers sites so I don't add create users statements also the only user that needs access to the database is the user executing the middle tire application.
I do not disable FK checks. I need them to protect the consistency of the database, even if it is I who wrote the body scripts. I use FK to capture my errors.
I do not include the entire script in one transaction. I require from the users to take a backup of the db before they run any db upgrade scripts. For creating of a new database there is nothing to protect so running in a transaction is unnecessary. For upgrades there are sometimes extensive changes to the db. A couple of years ago we switched from varchar to nvarchar in about 250 tables. Not something you would like to do in one transaction.
I would recommend you to generate one script per database and version control the scripts separately.
Direct answers, please ask if you need to expand on any point
* Should I include the CREATE DATABASE statement?
Normally I would include it since you are creating and owning the database.
* Should I create users for the database in the same script?
This is also a good idea, especially if your application uses specific users.
* Is correct to disable FK check before executing the body of the script?
If the script includes data population, then it helps to disable it so that the order is not too important, otherwise you can get into complex scripts to insert (without fk link), create fk record, update fk column.
* May I include the hole script in a transaction?
This is normally not a good idea. Especially if data population is included as the transaction can become quite unwieldy large. Since you are creating the database, just drop it and start again if something goes awry.
* Is better to generate 1 script per database than one script for all of them?
One per database is my recommendation so that they are isolated and easier to troubleshoot if the need arises.
For development purposes it's a good idea to create one script per database object (one script for each table, stored procedure, etc). If you check them into your source control system that way then developers can check out individual objects and you can easily keep track of versions and know what changed and when.
When you deploy you may want to combine the changes for each release into one single script. Tools like Red Gate SQL compare or Visual Studio Team System will help you do that.
Should I include the CREATE DATABASE statement?
Should I create users for the database in the same script?
That depends on your DBMS and your customer.
In an Oracle environment you will probably never be allowed to do such a thing (mainly because in the Oracle world a "database" is something completely different than e.g. in the PostgreSQL or MySQL world).
Sometimes the customer will have a DBA that won't let you create databases (or schemas or users - depending on the DBMS in use). So you will need to supply that information to the DBA in order for him/her to prepare the environment for your script.
May I include the hole script in a transaction?
That totally depends on the DBMS that you are using.
Some DBMS don't support transactional DDL and will implicitely commit any transaction when you execute a DDL statement, so you need to consider the order of your installation script.
For populating the tables with data I would definitely try to do that in a single transaction, but again this depends on your DBMS.
Some DBMS are faster if you commit only once or very seldomly (Oracle and PostgreSQL fall into this category) but will slow down if you commit more often.
Other DBMS handle smaller but more transactions better and will slow down if the transactions get too big (SQL Server and MySQL tend to fall into that direction)
The best practices will differ considerably on whether it is the first time set-up or a new version being pushed. For the first time set-up yes you need create database and create table scripts. For a new version, you need to script only the changes from the previous version, so no create database and no create table unless it is a new table. Now you need alter table statements becasue you don't want to lose the existing data. I do usually write stored procs, functions and views with a drop and create statment as dropping those pbjects doesn't generally affect the underlying data.
I find it best to create all database changes with scripts that are stored in source control under the version. So if a client is new, you run the create version 1.0 scripts, then apply all the other versions in order. If a client is just upgrading from version 1.2 to version 1.3, then you run just the scripts in version 1.3 source control repository. This would also include scripts to populate or add records to lookup tables.
For transactions you may want to break them up into several chunks not to leave a prod database locked in one transaction.
We also write reversal scripts to return to the old version if need be. This makes life easier if you have a part of a change that causes unanticipated problems on prod (usually performance issues).
I'm trying to find out if this is possible, but so far I haven't found out any good solutions. What I would like to achieve is write a stored procedure that can clone a database but without the stored data. That means all tables, views, constraints, keys and indexes should be included but without any data. Can it be done?
Sure - your stored proc would have to read the system catalog views to find out what objects are in the database, determine their potential dependencies, and then create a single or a collection of SQL scripts which re-create the database, and execute those.
It's possible - not very nice and easy to do. Especially the dependencies between objects might cause more headaches than first meets the eye....
You could also:
use something like SQL Server Management Studio (if you're on SQL Server - you didn't specify) and create the scripts manually, and just re-execute them on a separate server
use a "diff" tool like Redgate SQL Compare to compare two servers and have the second one brought up to date
I've successfully used the Microsoft SQL Server Database Publishing Wizard for this purpose. It's pretty straightforward, no coding needed. Here's a sample call:
sqlpubwiz script -d DatabaseName -S ServerName -schemaonly C:\Projects2\Junk\ DatabaseName.sql
I believe the default is to create both data and schema, but you can use the schemaonly parameter.
Download it here
In SQL Server you can roll through the system tables (sys.tables, sys.columns, etc.) and construct things one at a time. It's going to be very manual and error prone at the beginning, but it should become systematic pretty quickly.
Another way to do it is to write something in .Net using SMO. Check out this link:
http://www.sqlteam.com/article/scripting-database-objects-using-smo-updated