I'm using SQL Server 2005, and I would like to know how to access different result sets from within transact-sql. The following stored procedure returns two result sets, how do I access them from, for example, another stored procedure?
CREATE PROCEDURE getOrder (#orderId as numeric) AS
BEGIN
select order_address, order_number from order_table where order_id = #orderId
select item, number_of_items, cost from order_line where order_id = #orderId
END
I need to be able to iterate through both result sets individually.
EDIT: Just to clarify the question, I want to test the stored procedures. I have a set of stored procedures which are used from a VB.NET client, which return multiple result sets. These are not going to be changed to a table valued function, I can't in fact change the procedures at all. Changing the procedure is not an option.
The result sets returned by the procedures are not the same data types or number of columns.
The short answer is: you can't do it.
From T-SQL there is no way to access multiple results of a nested stored procedure call, without changing the stored procedure as others have suggested.
To be complete, if the procedure were returning a single result, you could insert it into a temp table or table variable with the following syntax:
INSERT INTO #Table (...columns...)
EXEC MySproc ...parameters...
You can use the same syntax for a procedure that returns multiple results, but it will only process the first result, the rest will be discarded.
I was easily able to do this by creating a SQL2005 CLR stored procedure which contained an internal dataset.
You see, a new SqlDataAdapter will .Fill a multiple-result-set sproc into a multiple-table dataset by default. The data in these tables can in turn be inserted into #Temp tables in the calling sproc you wish to write. dataset.ReadXmlSchema will show you the schema of each result set.
Step 1: Begin writing the sproc which will read the data from the multi-result-set sproc
a. Create a separate table for each result set according to the schema.
CREATE PROCEDURE [dbo].[usp_SF_Read] AS
SET NOCOUNT ON;
CREATE TABLE #Table01 (Document_ID VARCHAR(100)
, Document_status_definition_uid INT
, Document_status_Code VARCHAR(100)
, Attachment_count INT
, PRIMARY KEY (Document_ID));
b. At this point you may need to declare a cursor to repetitively call the CLR sproc you will create here:
Step 2: Make the CLR Sproc
Partial Public Class StoredProcedures
<Microsoft.SqlServer.Server.SqlProcedure()> _
Public Shared Sub usp_SF_ReadSFIntoTables()
End Sub
End Class
a. Connect using New SqlConnection("context connection=true").
b. Set up a command object (cmd) to contain the multiple-result-set sproc.
c. Get all the data using the following:
Dim dataset As DataSet = New DataSet
With New SqlDataAdapter(cmd)
.Fill(dataset) ' get all the data.
End With
'you can use dataset.ReadXmlSchema at this point...
d. Iterate over each table and insert every row into the appropriate temp table (which you created in step one above).
Final note:
In my experience, you may wish to enforce some relationships between your tables so you know which batch each record came from.
That's all there was to it!
~ Shaun, Near Seattle
There is a kludge that you can do as well. Add an optional parameter N int to your sproc. Default the value of N to -1. If the value of N is -1, then do every one of your selects. Otherwise, do the Nth select and only the Nth select.
For example,
if (N = -1 or N = 0)
select ...
if (N = -1 or N = 1)
select ...
The callers of your sproc who do not specify N will get a result set with more than one tables. If you need to extract one or more of these tables from another sproc, simply call your sproc specifying a value for N. You'll have to call the sproc one time for each table you wish to extract. Inefficient if you need more than one table from the result set, but it does work in pure TSQL.
Note that there's an extra, undocumented limitation to the INSERT INTO ... EXEC statement: it cannot be nested. That is, the stored proc that the EXEC calls (or any that it calls in turn) cannot itself do an INSERT INTO ... EXEC. It appears that there's a single scratchpad per process that accumulates the result, and if they're nested you'll get an error when the caller opens this up, and then the callee tries to open it again.
Matthieu, you'd need to maintain separate temp tables for each "type" of result. Also, if you're executing the same one multiple times, you might need to add an extra column to that result to indicate which call it resulted from.
Sadly it is impossible to do this. The problem is, of course, that there is no SQL Syntax to allow it. It happens 'beneath the hood' of course, but you can't get at these other results in TSQL, only from the application via ODBC or whatever.
There is a way round it, as with most things. The trick is to use ole automation in TSQL to create an ADODB object which opens each resultset in turn and write the results to the tables you nominate (or do whatever you want with the resultsets). you can also do it in DMO if you enjoy pain.
There are two ways to do this easily. Either stick the results in a temp table and then reference the temp table from your sproc. The other alternative is to put the results into an XML variable that is used as an OUTPUT variable.
There are, however, pros and cons to both of these options. With a temporary table, you'll need to add code to the script that creates the calling procedure to create the temporary table before modifying the procedure. Also, you should clean up the temp table at the end of the procedure.
With the XML, it can be memory intensive and slow.
You could select them into temp tables or write table valued functions to return result sets. Are asking how to iterate through the result sets?
Related
I have a stored procedure that takes one table, and doing merge to another table. I want to get a table of logs with the data of what happened to each row, without inserting the data to a table.
I understand a stored procedure cannot return a table, and therefore I thought about using a function, but as of my understanding a function can not make transformations on tables.
Is combining a stored procedure with a function the solution? Or is there any thing else that I am not aware of?
A stored procedure can certainly return a result set, which the client can consume directly just like a regular SELECT statement.
That said, there are a range of options, none of which are perfect. Each suits a different scenario, and are described at length by Erland Sommarskog in How to Share Data between Stored Procedures:
Table-valued Functions
Inline Functions
Multi-statement Functions
Using a Table
Sharing a Temp Table
Process-keyed Table
INSERT-EXEC
Using SQLCLR
OPENQUERY
XML
Cursor Variables
For example, you may not wish to use a permanent table, but a temporary table created by the client and populated by the stored procedure can work well, if directly consuming the results of a SELECT inside the procedure is not suitable.
I'm writing a stored procedure which checks for the existence of various tables in various databases, as well as the permissions that the user executing the stored procedure has on those tables. The stored procedure itself resides within a user database (i.e. it's not in the Master db).
To perform my checks, my stored procedure contains lots of SELECT statements. Each of those obviously returns a record set. What I would like is to somehow suppress these record sets so that they are not returned by the stored procedure, and instead return my own, single record set which is just a collection of messages relating to each check the stored procedure performs.
I think the obvious answer is to use a table-valued function instead, but I've not been able to recreate my tests successfully in a Function as they appear in the stored procedure. For starters, I'm having to use temporary tables (not possible in a function) and dynamic SQL (not very compatible with table parameters).
I think I've basically got two choices:
Rewrite my stored procedure as a function and figure out how to do the checks a different way.
Continue using my stored procedure and use an OUTPUT parameter to return my result messages, probably as a delimited string, and in the associated ASP.NET application just ignore all the record sets the stored procedure returns .
Neither of these solutions is very satisfactory. Before I spend any more time pursuing either one, is there a way to discard the record sets produced by the SELECT statements in a stored procedure and explicitly define what record I want it to return?
Hmm, I only can speculate here...
Are you using something like
SELECT ...;
IF ##rowcount > 0
BEGIN
...
END;
?
Then you can rewrite it using something like
IF EXISTS (SELECT ...)
BEGIN
...
END;
or
DECLARE #variable integer;
SELECT #variable = count(*) ...;
IF #variable > 0
BEGIN
...
END;
In general point the results of your queries to a target (variable, table, expression, ...), then they don't get outputted.
And then just execute the query for your desired result in the end.
In my opinion, here is almost no reason to have stored procedures produce record sets. That is what stored functions are for. On occasion, it is needed, because of the use of dynamic SQL or other stored procedures, but not as a general practice. Much, much too often, I see stored procedures being used where stored functions or views are more appropriate.
What should you do? Even SELECT statement in the stored procedure should be one of the following:
Setting (local) variables.
Saving the results in a temporary table or table variable.
The logic for the stored procedure should be working on the local variables. The results should be returned using OUTPUT parameters.
If you need to return rows in a tabular format, you can do that using tables explicitly (such as a global temporary table or real table). Or, you can have one SELECT at the end that does return a single result set. However, if you need this and can phrase the stored procedure as a function, that is better in my opinion.
I have a stored procedure that returns 4 result sets. The results sets have lots of columns.
What's the best way to create a table out of each result set? The data types and schema in the tables should be the same as the ones from the result sets.
I know I can do this to create a table from a selection:
CREATE TABLE TABLE_NAME
AS SELECT * FROM USERS
So is there a way to select a result set from a stored procedure execution??
While this was mostly covered in chat, it should still have an answer for others who might be wondering the same thing.
The only way to access a specific result set out of multiple results sets, and within the context of T-SQL, is via SQLCLR. Using C#, VB.Net, or any .Net language, you would use a SqlDataReader which can access the result sets separately.
The SQLCLR proc would simply exec the existing T-SQL proc and can either spit out a single result set (assuming an input param would specify which one to return as a result set) or could do a separate connection and directly call INSERT statements to do all 4 at the same time (although at that point it could just as well be a Console App or Windows Form or whatever).
I am calling a stored procedure in my current one and it returns 3 SELECT statements.
I need the first SELECT only.
How can I achieve this? I'm new to T-SQL, in C# I would just get those variables but SQL doesn't work that way.
Is it possible to get the values it returns?
I have 3 possibilities:
1) Make a new stored proc without the last 2 sSELECTs.
2) Pass an optional parameter to the stored proc to indicate if the last 2 SELECTs should run or not. (If the parameter is not passed, the SELECTs will run by default.)
3) Not an elegant solution, but this might work for your purposes:
In the second stored proc, output the first SELECT into a global temp table, then SELECT * from that temp table. (This will keep everything the same for anything else using the stored proc.)
In the first stored proc, select * from the temp table after you call the 2nd stored proc. (This will give you the results that you are looking for.) At the end of your first stored proc, drop the global temp table.
Some caveats:
If you have several people hitting the stored proc at once, this won't work with a single global temp table- you'll have to figure out some sort of naming convention so that each user gets their own separate table to play with.
If you have a lot of data in the result set, your tempdb database isn't going to be happy.
This question already has answers here:
SQL: how to predicate over stored procedure's result sets?
(3 answers)
Closed 6 years ago.
I currently have a stored procedure that runs a complex query and returns a data set. I'd like to cast this data set to a table (on which I can perform further queries) if at all possible. I know I can do this using a table-valued UDF but I'd prefer to avoid that at this point. Is there any way I can accomplish this task?
EDIT: OK... so the SProc I'm using (written by third party and I'm not supposed to change it) runs a fairly complex select statement to return a bunch of line item data about purchase orders. I can recreate it as a UDF but then I'd have to support the UDF and ensure it gets changed as and when our vendor changes their SProc. I'd like to further refine this line item info by a number of criteria such as (but not limited to) item numbers, vendor codes, cost centers, etc. All of this information is brought back by the original SProc and I just need to be able to manipulate it further. My thought process was that if I can somehow treat the results of the SProc as a table (or get them into a table format of some type) then I can run further queries against the original result set to limit by the criteria mentioned above. Please let me know if any further details are needed.
There's various means of sharing data between stored procedures - this link is pretty exhaustive.
But I'm curious why you want a table valued stored procedure (which doesn't exist in SQL Server) when there are table valued functions...
Cast Stored Procedure Result as a
Table?
Yes and this is used quite often. It simply needs one or more select statements:
Create Procedure #Foo
As
Select object_id, name
From sys.columns
That said, you cannot join to this resultset nor can you easily consume it from another stored proc (although there is a way). Given your edit, it appears the question is whether you can consume the results of a stored proc by another stored proc. Technically, yes. You can populate a temp table with the results of a proc. However, you must declare your temp variable or temp table with the same column structure as is returned by the first resultset of the stored proc.
Declare #Data Table ( object_id int, name nvarchar(128) )
Insert #Data
Exec #Foo
Select *
From #Data
(Or use the far more clever OPENROWSET solution as mentioned by Cade Roux and OMG Ponies)
Have you considered using table-valued parameters? They are new in SQL 2008.
-- Edit --
Nope, never mind, they're only good for passing data into stored procedures.
You could try using a View instead of a Stored Procedure. Store your complex query as part of the view, and you have the functionality to perform more queries on the view.