I know databases aren't supported by CREATE SYNONYM, but I'm looking to achieve the functionality this would provide.
We've got Database A which contains views to tables on Database B. The trouble is "Database B" isn't always called "Database B". We use database projects for deployments, which at the moment fall over with an "Invalid Object Name" error if there isn't a "Database B".
The workaround at the moment is to open up the .dbschema file and do a find and replace. I guess another option would be to create a load of table synonyms.
What's the best way of changing the database a number of views reference without changing each view individually?
Thanks
Synonyms are a good way to do this. You have to create the synonyms at the object level though (as you've discovered). An easy way to do this would be to write a script that runs through the list of tables in DatabaseB (from your example) and creates a synonym for each one in DatabaseA. Keep the name of the synonym the same so the code in your views doesn't have to change. For instance, you you have tbl_a, tbl_b, and tbl_c in DatabaseB, you'd want your script to eventually do the following:
create synonym [otherDb].[tbl_a] for [DatabaseB].[schemaB].[tbl_a]
create synonym [otherDb].[tbl_b] for [DatabaseB].[schemaB].[tbl_b]
create synonym [otherDb].[tbl_c] for [DatabaseB].[schemaB].[tbl_c]
Now, in your view code, you'll always use [otherDb].[tbl_a], [otherDb].[tbl_b], and [otherDb].[tbl_c]. Hope this makes sense.
Last year I helped my current client with the implementation of a very similar design. We wrote a set of functions and stored procedures which generate the views automatically. Whenever you need to change the target database it generates the code to drop and recreate all of the views.
The code wasn't too difficult. It just uses the system tables to generate view code. I also wrote a Powershell prototype that uses SMO to do the same thing. The key is to have it automated to the point of requiring a single call so that you can do it easily and accurately.
We also included an exception table that used a pattern match of tables to exclude from view generation. It included a schema column and a table name column, each of which accepted LIKE patterns, so you could put "my_schema" and "%" to exclude all tables in the my_schema schema.
One master stored procedure accepted a target database name and would generate the entire script. Once the script is generated you can run it in SSMS or have that part automated as well.
This whole thing would be even easier if you just wanted to generate synonyms. We were using views so that we could change column lists, etc. and have the view DB look different than the target DB where needed.
Related
EDIT: This question was based on the incorrect premise that SQL VIEWS were cleared from a database when the user that created them disconnects from the server. Leaving this question in existence in case others have that assumption.
I'm trying to use views in my database, but I'm running up against an inability to save the code as a SQL Server object for repeated use.
I tried saving CREATE VIEW statements as procedures and user defined functions, but as many have answered on stack overflow, CREATE PROCEDURE and CREATE FUNCTION are incompatible with CREATE VIEW due to the only one in batch issue.
Obviously I don't want to retype my CREATE VIEW statements every time, and I'd prefer not to have to load them from text files. I must be missing something here.
You don't really "save" CREATE/ALTER statements. The create or alter statement changes the structure of the database. You can use SSMS to generate the statement again later by right clicking on the view, and choosing Script as->Create. This inspects the structure of the database and generates the statement.
The problem with this approach is your database now consists of both a structure definition(DDL) as well as its contents, the data. If you dropped/created the database to clear its data, you'd also have lost the structure. So you always need a database hanging around for the structure and back it up to ensure you don't ever lose the DDL.
Personally I would use Database Projects as part of Visual Studio and SQL Server Data Tools. This allows you to keep each View, Table, etc. as separate files, and then update the database using schema compare. The main benefit being you can separate the definition of the database from the database itself, and also source control or backup the DDL files.
If you really want to, you could create a view in a proc like this:
CREATE PROCEDURE uspCreateView AS
EXEC('CREATE VIEW... ')
Though, you'll have to escape single quotes in your view code with ''
However, I have to agree with the other comments that this seems like a strange thing to do.
Some other thoughts:
You can use sp_helptext to get the code of an existing view:
sp_helptext '<your view name here>'
Also, INFORMATION_SCHEMA.VIEWS includes a VIEW_DEFINITION column with the same code:
SELECT * FROM INFORMATION_SCHEMA.VIEWS
I have a a system with two databases, main database and audit database. A lot of the triggers and table views in the main database and audit database are referencing from one database to the other. No I needed to change both databases names but unfortunately they failed to work because they still have the old names in the code.
Is there a code to search and replace the old name used for referencing or in dependence?
Thank you,
You will have to manually fix the references but you can leverage some sql to find the offending objects.
select OBJECT_NAME(id) as ObjectName
, text as ObjectCode
from sys.syscomments
where text like '%YourReplacedDatabaseName%'
That will give you a list of functions, procedures, views etc that have the old database name in the code. You will however have to recompile each object after you have updated the code. You could probably utilize some dynamic sql around this to do it for you but I would be nervous about changes on that scale automatically.
I recently used - EXEC sp_rename '<source table name>', '<destination table name>' to rename an existing table and want to execute the same on one of our live server. Is there any issue in using this procedure to rename a table?. I am asking this because one of our DBA says there will be problems in using this procedure on live server.
Is nothing referencing the table you're renaming? That would be the only instance where I would think renaming the table would not have an impact. If the table was not referenced by anything however, what would be the purpose of the table?
you can read more about sp_rename here:
http://msdn.microsoft.com/en-us/library/ms188351.aspx
Specifically note the following:
Renaming an object such as a table or column will not automatically
rename references to that object. You must modify any objects that
reference the renamed object manually. For example, if you rename a
table column and that column is referenced in a trigger, you must
modify the trigger to reflect the new column name. Use
sys.sql_expression_dependencies to list dependencies on the object
before renaming it.
There is no major issue with renaming the table using that procedure. The only thing you need to remember is that while that command is being executed, the locks that are applied on that table won't allow you to query the data, but that should only take only a couple of milliseconds, so you should be fine.
P.S. Don't forget to modify your views, procedures, functions etc :)
Below is the only caution as described inthe microsoft official web site.
Changing any part of an object name can break scripts and stored procedures. We recommend you do not use this statement to rename stored procedures, triggers, user-defined functions, or views; instead, drop the object and re-create it with the new name.
More details at : http://msdn.microsoft.com/en-us/library/ms188351.aspx
EXEC sp_rename is recommended only when we sure that all the depended SP, View function are not get affected. Make sureyou changed or deleted the depended objects.
Perhaps your DBA can share the details of his/her concerns. Renaming a table will of course be a breaking change for any objects that reference the table so you'll need to perform due diligence to ensure dependent objects are changed to use the new name. The rename operation will also require a short schema modification lock and void existing referencing cached plans, so be aware of this if the table is heavily used.
Following is my schema detail:
DB_A : schema_1, schema_2, schema_3
DB_B : schema_3
some procedures in schema_3 access resources(table, view, sp) from schema_1 and schema_2.
All procedures in schema_3 are same on both the dbs. How do I access schema_1 from schema_3 for both the dbs.
Now I can hard code DB_A in my procedures but when I move code to client machine, it will create a problem since DB_A may not be same(one of the reason being client is miser and having QA, Dev and Prod on same machine).
Second option is getting DB_A name as a parameter, but it will make all the schema_3 SPs dynamic (as I did not get any method to access something like #DBName.schema_name.ResourceName).
Third option is creating linked servers, which again do not solve my problem because of same reason as first.
Any idea how to proceed, where I do not want my procedures to be dynamic just because 80% of them are straight.
Edit Start:
So I can restate it as I have multiple databases with a database having resources (table/view/schema) which needs to be shared and then having other databases (one or more) which have stored procedures which computes on data from shared database and self database.
Shared database name is not going to be constant on all the environments and I want to change them(environment specific). I have come out with a solution where I will be creating synonym for all the shared resources and all procedures will be using them, that way they are all referring to shared resources from first database.
For each installation I need to modify synonyms definition to reflect correct share database name. Is there any SYNONYM For Database Name, that way I will have way less synonyms to handle.
Well the best choice I found is as follows.
Create Synonym (independent database DB_B) for individual objects (in shared database DB_A) with same name in same schema. That way your existing procedures need not change, and will work as required. Synonym gives a good reference on this. I will soon be creating an app to ease creating synonyms for these kind of situations.
CREATE SYNONYM DB_B.schema_1.proc_1 FOR DB_A.schema_1.proc_1
You can run your procedure in DB_A and create a view from DB_A to DB_B:
create view dbo.vw_B_Schema_3
as
select *
from DB_B.dbo.Schema_3
You'd have to create three versions of the view (dev, QA, prod.) But the view will be the only difference: procedure definitions can remain identical.
If DB_A and DB_B are on same server, only sure you that the login have permission in two database.
Now, use [database].[schema].[object], when you use object of others database
eg: I have two database, ("helpdesk", "intranet")
from heldesk to intranet
create view dbo.users
as
select login, name, lastname
from intranet.dbo.user // [database].[schema].[object] user is a table in dbo schema from intranet database.
where status = 1
;
I have an assortment of database objects (tables, functions, views, stored procedures) each scripted into its own file (constraints are in the same file as the table they alter) that I'd like to be able execute in an arbitrary order. Is this possible in SQL Server 2005?
Some objects as an example:
Table A (references Table B)
Table B (references Function A)
Function A (references View A)
View A (references Table C)
Must be run in the following order:
Table C
View A
Function A
Table B
Table A
If the scripts are run out of order, errors about the missing objects are thrown.
The reason I ask is that in a project I'm working on we maintain each database object in its own file (for source control purposes), and then maintain a master script that creates each database object in the correct order. This requires the master script to be manually edited any time an object is added to the schema. I'd like to be able to just execute each script as it is found in the file system.
In my experience the most problematic issue is with views, which can reference recursively. I once wrote a utility to iterate through the scripts until the errors were all resolved. Which only works when you're loading everything. Order was important - I think I did UDTs, tables, FKs, views (iteratively), SPs and UDFs (iteratively until we decided that SPs calling SPs was a bad idea, and UDFs are generally a bad idea.)
If you script the foreign keys into separate files, you can get rid of table-table dependencies, if you run the FK script after creating all tables.
As far as I'm aware, functions and procedures check for object existence only in JOIN clauses.
The only difficulty I found was views depending on views, as a view definition requires that the objects the view depends on do exist.
I found this page where the author has written a nice procedure for doing exactly what you are talking about. Sounds like you just need to have two versions of it, one for disabling the constraints and another to re-enable then.
APEX SQL Script is supposed to analyze the dependencies and order the script appropriately, but even then I've had problems.