Comments on: SQL SERVER – Getting Columns Headers without Result Data – SET FMTONLY ON

By: Janet Steen

Janet Steen — Tue, 30 Oct 2012 20:39:51 +0000

Paul – Thank you very much for sharing this post. Been struggling with Entity Framework in VS because of this.

By: Nick

Nick — Mon, 01 Oct 2012 00:38:34 +0000

To expand a bit on what Paul said,

If you’re using an ORM mapper (we use ADO.NET entity framework) sometimes it will not be able to see the result set properly when you’re trying to setup your mappings. If you watch it in profiler, the framework will open a connection to the DB, SETS FMTONLY ON, then runs the proc with all NULL values passed in for the parameters.

It works most of the time, but I occasionally Entity Framework will just report an empty result set. I haven’t seen any pattern to my SQL code when this happens, but the only fix I’ve come across so far is to add SET FMTONLY OFF within the procedure’s definition and redeploy the SQL code.

By: SQL SERVER – Copy Column Headers from Resultset – SQL in Sixty Seconds #026 – Video « SQL Server Journey with SQL Authority

Wed, 26 Sep 2012 01:31:42 +0000

[...] Getting Columns Headers without Result Data – SET FMTONLY ON [...]

By: manojb

manojb — Mon, 17 Sep 2012 04:23:25 +0000

Hi pinal , Inside set FMT ony on does not allow Go Statement .What i do
For ex:
Set Fmt only on

Select * from Tables1

Update table1 set id =@id where name =@name

I got Error .what i do

By: Patrick

Patrick — Mon, 09 Jul 2012 22:04:46 +0000

Select into a temp table, say #mytemp, and do this:

SELECT COLUMN_NAME FROM tempdb.INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME LIKE ‘#mytemp%’

And you will get a vertical list of the column names. You can add metadata or whatever else from INFORMATION_SCHEMA as well, of course.

By: Aafreen Sheikh

Aafreen Sheikh — Wed, 21 Mar 2012 09:03:12 +0000

Hi Pinal, is there a way I could get a “vertical” list of columns..I am interested in just the number of columns being returned..It’s like saying “Is there an equivalent of count(*) to count the number of columns returned by a stored procedure”?

By: Paul Russo

Paul Russo — Wed, 04 Jan 2012 11:58:57 +0000

Hi Pinal – I found it very useful to get the ADO.NET DataSet Schema fill to work – and the LINQ2SQL designer to work – where I have used a temporary table in a stored procedure. In this case you may get an error message saying the temporary table could not be found – after some digging around I came across the FMTONLY option and hence your post.

I found that if I set the set fmtonly off; just before I created a temporary table and set fmtonly on; just after I created the table then the schema could be read quite happily (I had joined on the temporary table for the final SELECT) – with both ADO.NET DataSets and the LINQ2SQL designer. Apparently the ADO.NET and LINQ tools uses the FMTONLY option internally against the entire stored procedure – my fix just overrode it enough to allow temp table to be parsed as well.

By: madhivanan

madhivanan — Thu, 02 Jun 2011 09:33:36 +0000

Yes thats the simple solution without worrying much on SET OPTIONS

By: madhivanan

madhivanan — Thu, 02 Jun 2011 09:27:07 +0000

If you want to know the column names quickly it is helpful

By: Ashish Kadam

Ashish Kadam — Thu, 02 Jun 2011 05:52:25 +0000

Hi Pinal, I Am Not Understanding That What’s Use Of It In Practical Scenario. In Which Situation It’s Helpful to The Developer also?

By: Jay

Jay — Wed, 01 Jun 2011 21:28:13 +0000

Hi Pinal Also what do you think about this to get column names?
SELECT * FROM Table WHERE 1=0

I don’t have to mess with the SET OPTIONS and the execution plan is doing/does a constant scan ( I also tested it on a 10 TB table)

By: DiGi

DiGi — Thu, 26 May 2011 08:02:47 +0000

This is most stupid feature ever. ADO components sometimes add SET FMTONLY ON and make dry run.

But FMTONLY ignore logical statements, so this is VALID part of code:

CREATE PROCEDURE dbo.RunSomeCode(@Param VARCHAR(10))
AS

IF 1=2 — YEAH we are in FMTONLY
BEGIN
SET FMTONLY OFF
— OR EXIT procedure
END
..
..

otherwise:

SELECT
a, b
INTO
#TABLE
FROM
SomeTable

SELECT * FROM #Table -> FAIL, because #Table will not be created

– @Foo = ”
SET @mark = CHARINDEX(‘X’, @Foo)
IF @mark > 0 — WITH FMTONLY this will pass
BEGIN
SET @SubStr = SUBSTRING(.. ) — Error here
END

By: Diyan

Diyan — Thu, 26 May 2011 06:29:45 +0000

Is there any difference if I use WHERE 1=2 ?

By: Farhad Farahmandkhah

Farhad Farahmandkhah — Thu, 26 May 2011 06:11:59 +0000

Thanks

By: Feodor

Feodor — Thu, 26 May 2011 06:02:49 +0000

One time, at a client, I noticed that many events in the profiler were showing with suspiciously high amount of reads.
I looked into that, and noticed that the bactches were preceded with FMTONLY statements, and in profiler both events had as much reads.
At the time I was surprised, since the FMTONLY ON should have a few reads, since it just returns the metadata, not the entire resultset.
Could you please explain what the processing routine of a FMTONLY statement looks like – i.e. is the statement parsed, algebrized, optimized and so on?

Thank you.

By: Prasoon Pathak

Prasoon Pathak — Thu, 26 May 2011 03:47:33 +0000

Hi Pinal,

is it helpfull in select * into statements
or
creating the schema of empty datatable in dot net…