i have a query which returns unconstant number of columns.
How can i use this in reporting services?
SET #aaa = ( 'select '+ #str+ ' from personel.fnt_hede(1,21,0) ')
EXECUTE (#aaa )
somehow i generate #str and use in this way.
I hope , i expressed myself clearly :)
thanks in advance..
One option, is to return a fixed set of columns (assuming there is a definable set) and then show/hide the appropriate columns in the report.
Or, you could use a Matrix in your report. You would have to return data in a different approach though, basically as a list of key/value data values that the Matrix can pivot. Here's a post that came in handy when I was looking into this scenario. This approach turned out to work well in a situation where I too do not know up front how many columns (or what their names are going to be) up front.
You can't - SSRS needs a clearly defined resultset to be able to design reports.
Instead of using a custom query, use a query with all the available fields included, and then pass parameter values to the report to indicate which ones should be displyed.
Related
Thank you for checking my question out!
I'm trying to write a query for a very specific problem we're having at my workplace and I can't seem to get my head around it.
Short version: I need to be able to target columns by their name, and more specifically by a part of their name that will be consistent throughout all the columns I need to combine or compare.
More details:
We have (for example), 5 different surveys. They have many questions each, but SOME of the questions are part of the same metric, and we need to create a generic field that keeps it. There's more background to the "why" of that, but it's pretty important for us at this point.
We were able to kind of solve this with either COALESCE() or CASE statements but the challenge is that, as more surveys/survey versions continue to grow, our vendor inevitably generates new columns for each survey and its questions.
Take this example, which is what we do currently and works well enough:
CASE
WHEN SURVEY_NAME = 'Service1' THEN SERV1_REC
WHEN SURVEY_NAME = 'Notice1' THEN FNOL1_REC
WHEN SURVEY_NAME = 'Status1' THEN STAT1_REC
WHEN SURVEY_NAME = 'Sales1' THEN SALE1_REC
WHEN SURVEY_NAME = 'Transfer1' THEN Null
ELSE Null
END REC
And also this alternative which works well:
COALESCE(SERV1_REC, FNOL1_REC, STAT1_REC, SALE1_REC) as REC
But as I mentioned, eventually we will have a "SALE2_REC" for example, and we'll need them BOTH on this same statement. I want to create something where having to come into the SQL and make changes isn't needed. Given that the columns will ALWAYS be named "something#_REC" for this specific metric, is there any way to achieve something like:
COALESCE(all columns named LIKE '%_REC') as REC
Bonus! Related, might be another way around this same problem:
Would there also be a way to achieve this?
SELECT (columns named LIKE '%_REC') FROM ...
Thank you very much in advance for all your time and attention.
-Kendall
Table and column information in Db2 are managed in the system catalog. The relevant views are SYSCAT.TABLES and SYSCAT.COLUMNS. You could write:
select colname, tabname from syscat.tables
where colname like some_expression
and syscat.tabname='MYTABLE
Note that the LIKE predicate supports expressions based on a variable or the result of a scalar function. So you could match it against some dynamic input.
Have you considered storing the more complicated properties in JSON or XML values? Db2 supports both and you can query those values with regular SQL statements.
We are attempting to concatenate possibly thousands of rows of text in SQL with a single query. The query that we currently have looks like this:
DECLARE #concatText NVARCHAR(MAX)
SET #concatText = ''
UPDATE TOP (SELECT MAX(PageNumber) + 1 FROM #OrderedPages) [#OrderedPages]
SET #concatText = #concatText + [ColumnText] + '
'
WHERE (RTRIM(LTRIM([ColumnText])) != '')
This is working perfectly fine from a functional standpoint. The only issue we're having is that sometimes the ColumnText can be a few kilobytes in length. As a result, we're filling up tempDB when we have thousands of these rows.
The best reason that we have come up with is that as we're doing these updates to #concatText, SQL is using implicit transactions so the strings are effectively immutable.
We are trying to figure out a good way of solving this problem and so far we have two possible solutions:
1) Do the concatenation in .NET. This is an OK option, but that's a lot of data that may go back across the wire.
2) Use .WRITE which operates in a similar fashion to .NET's String.Join method. I can't figure out the syntax for this as BoL doesn't cover this level of SQL shenanigans.
This leads me to the question: Will .WRITE work? If so, what's the syntax? If not, are there any other ways to do this without sending data to .NET? We can't use FOR XML because our text may contain illegal XML characters.
Thanks in advance.
I'd look at using CLR integration, as suggested in #Martin's comment. A CLR aggregate function might be just the ticket.
What exactly is filling up tempdb? It cannot be #concatText = #concatText + [ColumnText], there is no immutability involved and the #concatText variable will be at worst case 2GB size (I expect your tempdb is much larger than that, if not increase it). It seems more like your query plan creates a spool for haloween protection and that spool is the culprit.
As a generic answer, using the UPDATE ... SET #var = #var + ... for concatenation is known to have correctness issues and is not supported. Alternative approaches that work more reliably are discussed in Concatenating Row Values in Transact-SQL.
First, from your post, it isn't clear whether or why you need temp tables. Concatenation can be done inline in a query. If you show us more about the query that is filling up tempdb, we might be able to help you rewrite it. Second, an option that hasn't been mentioned is to do the string manipulation outside of T-SQL entirely. I.e., in your middle-tier query for the raw data, do the manipulation and push it back to the database. Lastly, you can use Xml such that the results handle escapes and entities properly. Again, we'd need to know more about what and how you are trying to accomplish.
Agreed..A CLR User Defined Function would be the best approach for what you guys are doing. You could actually read the text values into an object and then join them all together (inside the CLR) and have the function spit out a NVARCHAR(MAX) result. If you need details on how to do this let me know.
so i have a table lets say call it "tbl.items" and there is a column "title" in "tbl.items" i want to loop through each row and for each "title" in "tbl.items" i want to do following:
the column has the datatype nvarchar(max) and contains a string...
filter the string to remove words like in,out, where etc (stopwords)
compare the rest of the string to a predefined list and if there is a match perform some action which involves inserting data in other tables as well..
the problem is im ignotent when it comes to writing T-sql scripts, plz help and guide me how can i achieve this?
whether it can be achieved by writing a sql script??
or i have to develope a console application in c# or anyother language??
im using mssql server 2008
thanks in advance
You want a few things. First, look up SQL Server's syntax for functions, and write something like this:
-- Warning! Code written off the top of my head,
-- don't expect this to work w/copy-n-paste
create function removeStrings(#input nvarchar(4000))
as begin
-- We're being kind of simple-minded and using strings
-- instead of regular expressions, so we are assuming a
-- a space before and after each word. This makes this work better:
#input = ' ' + #input
-- Big list of replaces
#input = replace(' in ','',#input)
#input = replace(' out ','',#input)
--- more replaces...
end
Then you need your list of matches in a table, call this "predefined" with a column "matchString".
Then you can retrieve the matching rows with:
select p.matchString
from items i
join predefined p
on removeStrings(i.title) = p.matchString
Once you have those individual pieces working, I suggest a new question on what particular process you may be doing with them.
Warning: Not knowing how many rows you have or how often you have to do this (every time a user saves something? Once/day?), this will not exactly be zippy, if you know what I mean. So once you have these building blocks in hand, there may also be a follow-up question for how and when to do it.
I'm here to share a consolidated analysis for the following scenario:
I've an 'Item' table and I've a search SP for it. I want to be able to search for multiple ItemCodes like:
- Table structure : Item(Id INT, ItemCode nvarchar(20))
- Filter query format: SELECT * FROM Item WHERE ItemCode IN ('xx','yy','zz')
I want to do this dynamically using stored procedure. I'll pass an #ItemCodes parameter which will have comma(',') separated values and the search shud be performed as above.
Well, I've already visited lot of posts\forums and here're some threads:
Dynamic SQL might be a least complex way but I don't want to consider it because of the parameters like performance,security (SQL-Injection, etc..)..
Also other approaches like XML, etc.. if they make things complex I can't use them.
And finally, no extra temp-table JOIN kind of performance hitting tricks please.
I've to manage the performance as well as the complexity.
T-SQL stored procedure that accepts multiple Id values
Passing an "in" list via stored procedure
I've reviewed the above two posts and gone thru some solutions provided, here're some limitations:
http://www.sommarskog.se/arrays-in-sql-2005.html
This will require me to 'declare' the parameter-type while passing it to the SP, it distorts the abstraction (I don't set type in any of my parameters because each of them is treated in a generic way)
http://www.sqlteam.com/article/sql-server-2008-table-valued-parameters
This is a structured approach but it increases complexity, required DB-structure level changes and its not abstract as above.
http://madprops.org/blog/splitting-text-into-words-in-sql-revisited/
Well, this seems to match-up with my old solutions. Here's what I did in the past -
I created an SQL function : [GetTableFromValues] (returns a temp table populated each item (one per row) from the comma separated #ItemCodes)
And, here's how I use it in my WHERE caluse filter in SP -
SELECT * FROM Item WHERE ItemCode in (SELECT * FROM[dbo].[GetTableFromValues](#ItemCodes))
This one is reusable and looks simple and short (comparatively of course). Anything I've missed or any expert with a better solution (obviously 'within' the limitations of the above mentioned points).
Thank you.
I think using dynamic T-SQL will be pragmatic in this scenario. If you are careful with the design, dynamic sql works like a charm. I have leveraged it in countless projects when it was the right fit. With that said let me address your two main concerns - performance and sql injection.
With regards to performance, read T-SQL reference on parameterized dynamic sql and sp_executesql (instead of sp_execute). A combination of parameterized sql and using sp_executesql will get you out of the woods on performance by ensuring that query plans are reused and sp_recompiles avoided! I have used dynamic sql even in real-time contexts and it works like a charm with these two items taken care of. For your satisfaction you can run a loop of million or so calls to the sp with and without the two optimizations, and use sql profiler to track sp_recompile events.
Now, about SQL-injection. This will be an issue if you use an incorrect user widget such as a textbox to allow the user to input the item codes. In that scenario it is possible that a hacker may write select statements and try to extract information about your system. You can write code to prevent this but I think going down that route is a trap. Instead consider using an appropriate user widget such as a listbox (depending on your frontend platform) that allows multiple selection. In this case the user will just select from a list of "presented items" and your code will generate the string containing the corresponding item codes. Basically you do not pass user text to the dynamic sql sp! You can even use slicker JQuery based selection widgets but the bottom line is that the user does not get to type any unacceptable text that hits your data layer.
Next, you just need a simple stored procedure on the database that takes a param for the itemcodes (for e.g. '''xyz''','''abc'''). Internally it should use sp_executesql with a parameterized dynamic query.
I hope this helps.
-Tabrez
This is hopefully just a simple question involving performance optimizations when it comes to queries in Sql 2008.
I've worked for companies that use Stored Procs a lot for their ETL processes as well as some of their websites. I've seen the scenario where they need to retrieve specific records based on a finite set of key values. I've seen it handled in 3 different ways, illustrated via pseudo-code below.
Dynamic Sql that concatinates a string and executes it.
EXEC('SELECT * FROM TableX WHERE xId IN (' + #Parameter + ')'
Using a user defined function to split a delimited string into a table
SELECT * FROM TableY INNER JOIN SPLIT(#Parameter) ON yID = splitId
USING XML as the Parameter instead of a delimited varchar value
SELECT * FROM TableZ JOIN #Parameter.Nodes(xpath) AS x (y) ON ...
While I know creating the dynamic sql in the first snippet is a bad idea for a large number of reasons, my curiosity comes from the last 2 examples. Is it more proficient to do the due diligence in my code to pass such lists via XML as in snippet 3 or is it better to just delimit the values and use an udf to take care of it?
There is now a 4th option - table valued parameters, whereby you can actually pass a table of values in to a sproc as a parameter and then use that as you would normally a table variable. I'd be preferring this approach over the XML (or CSV parsing approach)
I can't quote performance figures between all the different approaches, but that's one I'd be trying - I'd recommend doing some real performance tests on them.
Edit:
A little more on TVPs. In order to pass the values in to your sproc, you just define a SqlParameter (SqlDbType.Structured) - the value of this can be set to any IEnumerable, DataTable or DbDataReader source. So presumably, you already have the list of values in a list/array of some sort - you don't need to do anything to transform it into XML or CSV.
I think this also makes the sproc clearer, simpler and more maintainable, providing a more natural way to achieve the end result. One of the main points is that SQL performs best at set based/not looping/non string manipulation activities.
That's not to say it will perform great with a large set of values passed in. But with smaller sets (up to ~1000) it should be fine.
UDF invocation is a little bit more costly than splitting the XML using the built-in function.
However, this only needs to be done once per query, so the performance difference will be negligible.