Is it possible to execute a view with a stored procedure?
My procedure should first run the views (I have 2 in total) and then am combining these 2 views data into a different table for applying transformations.
Something like this:
create or replace procedure procname as
begin
here my views should get triggered and then starts my
execute immediate 'truncate table transtable';
insert
...
.....
...
exception
end;
What do you call "execute a view with stored procedure"? How are views "triggered"?
If you meant to ask whether you can create views in a procedure - then yes, you can - using execute immediate. Though, in Oracle, that's highly unusual practice. We create views first (at SQL level), use them everywhere (in SQL or PL/SQL) and that's what I'd suggest you to do.
If you ask why?, reason is simple: dynamic SQL doesn't scale, it is difficult to maintain and debug, and - if there's nothing "dynamic" in it, don't use it.
Moreover, if you reference those views later in your code (and they don't exist at time of compilation), PL/SQL procedure will fail with ORA-00942 (table or view doesn't exist) which means that the rest of your code should also be dynamic.
Nightmare at the horizon, in my opinion.
From what you posted so far, I don't see why would you insist on doing that dynamically:
create view "now" at SQL level
use them in the procedure
In short, I'm managing a bunch of versioned SQL Scripts where one requirement is that they need to be sort of backwards compatible in that the same scripts can be executed multiple times, still guaranteeing the same end result for the latest version. Basically, say we are on version 3. We need to be able to run scripts for versions 1, 2 and 3 over and over, without errors, and still guarantee that the end result is the same complete version 3.
Now this is easy with normal scenarios (just check if column / table / type is right and create / modify if not), but how do you deal with for instance a trigger that's way over 8000 characters long and can't be executed as dynamic SQL? As version 2 is installed, the triggers are dropped, at the end, new ones are created to match v2's datamodel. But if v3 removed one of the columns referred to by the v2 trigger, that trigger will now fail.
I can't make any kind of IF checks to see if our log has v3 scripts, or if the datamodel doesn't match the requirements. I'd hate to make others do manual labor to do something I'm sure can be automated one way or another. So is there any nice gimmick, trick or just something I missed that could help?
Thanks for the help. :)
but how do you deal with for instance a trigger that's way over 8000
characters long and can't be executed as dynamic SQL?
It can be executed using sp_executesql for which size of sql statement is limited only by available database server memory.
You need to check if object exists and create it if you need or delete otherwise.
if object_id(N'your_table_name','U') is null
CREATE TABLE
...
GO
/* add column */
if not exists (select * from sys.columns
where object_id=object_id('TableName','U') and name='ColumnName')
ALTER TABLE TableName
ADD ColumnName
GO
/* creating Stored Procedure */
if object_id(N'ProcedureName','P') is null
EXEC sp_executesql N'CREATE PROCEDURE ProcedureName AS print 1'
GO
ALTER PROCEDURE ProcedureName
AS
/*your actual code here*/
GO
/* and so on */
Object types for object_id function you can see here.
I have an user defined table type (UDTT) that is already bound with a stored procedure which uses it as a input parameter. I have made a mistake in UDTT structure but I cannot alter UDTT so when I tried to delete it, SSMS complaints that its bound to store procedure so it cannot be deleted. Is there away to delete my UDTT?
thanks
It is required on the drop, and what I normally do is set myself a template script that follows this execution:
-- Table builds or the type
if object_id(N'dbo.<tablename>') is null
begin <create table chunk> end
-- Proc Drops
-- UDTT Drops
-- UDTT Adds
-- Proc Adds
Then if you ever need to Alter a proc, you just seek it on that script and execute the script again. Since there is no saved data in a procedure, this solves type overlooks as well as recompile options needing processed. I found it to make development as well as testing much more conducive.
There is an easy work around here. I use SSMS, and select
SCRIPT AS > CREATE TO > NEW QUERY EDITOR WINDOW.
This gives a script to create. I then rename the existing data type rather than deleting it. Make whatever changes are needed to the recreate script, and execute.
You can then drop the renamed data type.
Its a bit of a work around, and an alter command would be better, but this does the job.
I want to create a temporary stored procedure to create several views; so something like this:
create proc #t1 as
begin
create view v1 as select 1 as x
go
create view v2 as select 2 as x
end
Unfortunately, when I execute this in Microsoft SQL Server 2005, I get a syntax error on the first create view line.
Something like this works:
create proc #t1 as
begin
exec('create view v1 as select 1 as x')
exec('create view v2 as select 2 as x')
end
However, this seems like a terrible way of doing what I want.
So what's wrong with the first attempt, and what's the best way to create multiple views in a stored procedure?
You can't have a go inside a stored procedure. It's not a command in SQL, it's a separator between batches in the SQL Manager, so it will cut the procedure into two batches and cause syntax errors because neither batch is a complete command.
You don't have to write a full blown parser to make this work - all you need to do is what the command line tools/SSMS do - read lines from the file and accumulate them in a (in .Net, it's a stringbuilder, can't remember the equivalent in Java) until you encounter a line which starts with the word GO. Each time you reach that point, send your accumulated buffer to SQL Server, and then empty your buffer and start again.
So long as your current script has GO whenever it's required, the above should work.
This is easy you can achieve this using variable,assign the create view to the #variable then EXEC(#Variable) statements inside the procedure
When it comes to creating stored procedures, views, functions, etc., is it better to do a DROP...CREATE or an ALTER on the object?
I've seen numerous "standards" documents stating to do a DROP...CREATE, but I've seen numerous comments and arguments advocating for the ALTER method.
The ALTER method preserves security, while I've heard that the DROP...CREATE method forces a recompile on the entire SP the first time it's executed instead of just a a statement level recompile.
Can someone please tell me if there are other advantages / disadvantages to using one over the other?
ALTER will also force a recompile of the entire procedure. Statement level recompile applies to statements inside procedures, eg. a single SELECT, that are recompiled because the underlying tables changes, w/o any change to the procedure. It wouldn't even be possible to selectively recompile just certain statements on ALTER procedure, in order to understand what changed in the SQL text after an ALTER procedure the server would have to ... compile it.
For all objects ALTER is always better because it preserves all security, all extended properties, all dependencies and all constraints.
This is how we do it:
if object_id('YourSP') is null
exec ('create procedure dbo.YourSP as select 1')
go
alter procedure dbo.YourSP
as
...
The code creates a "stub" stored procedure if it doesn't exist yet, otherwise it does an alter. In this way any existing permissions on the procedure are preserved, even if you execute the script repeatedly.
Starting with SQL Server 2016 SP1, you now have the option to use CREATE OR ALTER syntax for stored procedures, functions, triggers, and views. See CREATE OR ALTER – another great language enhancement in SQL Server 2016 SP1 on the SQL Server Database Engine Blog. For example:
CREATE OR ALTER PROCEDURE dbo.MyProc
AS
BEGIN
SELECT * FROM dbo.MyTable
END;
Altering is generally better. If you drop and create, you can lose the permissions associated with that object.
If you have a function/stored proc that is called very frequently from a website for example, it can cause problems.
The stored proc will be dropped for a few milliseconds/seconds, and during that time, all queries will fail.
If you do an alter, you don't have this problem.
The templates for newly created stored proc are usually this form:
IF EXISTS (SELECT * FROM sysobjects WHERE type = 'P' AND name = '<name>')
BEGIN
DROP PROCEDURE <name>
END
GO
CREATE PROCEDURE <name>
......
However, the opposite is better, imo:
If the storedproc/function/etc doesn't exist, create it with a dummy select statement. Then, the alter will always work - it will never be dropped.
We have a stored proc for that, so our stored procs/functions usually like this:
EXEC Utils.pAssureExistance 'Schema.pStoredProc'
GO
ALTER PROCECURE Schema.pStoredProc
...
and we use the same stored proc for functions:
EXEC Utils.pAssureExistance 'Schema.fFunction'
GO
ALTER FUNCTION Schema.fFunction
...
In Utils.pAssureExistance we do a IF and look at the first character after the ".": If it's a "f", we create a dummy fonction, if it's "p", we create a dummy stored proc.
Be careful though, if you create a dummy scalar function, and your ALTER is on a table-valued function, the ALTER FUNCTION will fail, saying it's not compatible.
Again, Utils.pAssureExistance can be handy, with an additional optional parameter
EXEC Utils.pAssureExistance 'Schema.fFunction', 'TableValuedFunction'
will create a dummy table-valued function,
Additionaly, I might be wrong, but I think if you do a drop procedure and a query is currently using the stored proc, it will fail.
However, an alter procedure will wait for all queries to stop using the stored proc, and then alter it. If the queries are "locking" the stored proc for too long (say a couple seconds), the ALTER will stop waiting for the lock, and alter the stored proc anyway: the queries using the stored proc will probably fail at that point.
DROP generally loses permissions AND any extended properties.
On some UDFs, ALTER will also lose extended properties (definitely on SQL Server 2005 multi-statement table-valued functions).
I typically do not DROP and CREATE unless I'm also recreating those things (or know I want to lose them).
I don't know if it's possible to make such blanket comment and say "ALTER is better". I think it all depends on the situation. If you require this sort of granular permissioning down to the procedure level, you probably should handle this in a separate procedure. There are benefits to having to drop and recreate. It cleans out existing security and resets it what's predictable.
I've always preferred using drop/recreate. I've also found it easier to store them in source control. Instead of doing .... if exists do alter and if not exists do create.
With that said... if you know what you're doing... I don't think it matters too much.
If you perform a DROP, and then use a CREATE, you have almost the
same effect as using an ALTER VIEW statement. The problem is that you need to entirely re-establish your permissions on who can and can’t use the view. ALTER retains any dependency information and set permissions.
You've asked a question specifically relating to DB objects that do not contain any data, and theoretically should not be changed that often.
Its likely you may need to edit these objects but not every 5 minutes. Because of this I think you've already hit the hammer on the head - permissions.
Short answer, not really an issue, so long as permissions are not an issue
We used to use alter while we were working in development either creating new functionality or modifying the functionality. When we were done with our development and testing we would then do a drop and create. This modifys the date/time stamp on the procs so you can sort them by date/time.
It also allowed us to see what was bundeled by date for each deliverable we sent out.
Add with a drop if exists is better because if you have multiple environments when you move the script to QA or test or prod you don't know if the script already exists in that environment. By adding an drop (if it already exists) and and then add you will be covered regardless if it exists or not. You then have to reapply permissions but its better then hearing your install script error-ed out.
From a usability point of view a drop and create is better than a alter. Alter will fail in a database that doesn't contain that object, but having an IF EXISTS DROP and then a CREATE will work in a database with the object already in existence or in a database where the object doesn't exist. In Oracle and PostgreSQL you normally create functions and procedures with the statement CREATE OR REPLACE that does the same as a SQL SERVER IF EXISTS DROP and then a CREATE. It would be nice if SQL Server picked up this small but very handy syntax.
This is how I would do it. Put all this in one script for a given object.
IF EXISTS ( SELECT 1
FROM information_schema.routines
WHERE routine_schema = 'dbo'
AND routine_name = '<PROCNAME'
AND routine_type = 'PROCEDURE' )
BEGIN
DROP PROCEDURE <PROCNAME>
END
GO
CREATE PROCEDURE <PROCNAME>
AS
BEGIN
END
GO
GRANT EXECUTE ON <PROCNAME> TO <ROLE>
GO