Is this better to do as below:
create table #tv_target (c11 int, c22 char(100))
go

INSERT INTO #tv_target (c11, c22)
SELECT c1, c2 FROM tv_source

or is it better to do as below:
SELECT c1, c2 into #tv_target
FROM tv_source

please,How can I programaticaly get the structure of Table variable ?.

i can get the name from sys.type but not the metada.

need help.

use tempdb

go

drop table #tv_source

go

create table #tv_source(c1 int, c2 char(8000))

go

declare @i int

select @i = 0

while (@i 100 and name like ‘c%’

This will return two rows containing columns c111 and c222. Now this means that if you were encountering DDL contention, you cannot address it by changing a #table to table variable.

· Third, transactional and locking semantics. Table variables don’t participate in transactions or locking. Here is one example

– create a source table

create table tv_source(c1 int, c2 char(100))

go

declare @i int

select @i = 0

while (@i < 100)

begin

insert into tv_source values (@i, replicate ('a', 100))

select @i = @i + 1

end

– using #table

create table #tv_target (c11 int, c22 char(100))

go

BEGIN TRAN

INSERT INTO #tv_target (c11, c22)

SELECT c1, c2

FROM tv_source

– using table variable

DECLARE @tv_target TABLE (c11 int, c22 char(100))

BEGIN TRAN

INSERT INTO @tv_target (c11, c22)

SELECT c1, c2

FROM tv_source

– Now if I look at the locks, you will see that only

– #table takes locks. Here is the query that used

– to check the locks

select

t1.request_session_id as spid,

t1.resource_type as type,

t1.resource_database_id as dbid,

(case resource_type

WHEN 'OBJECT' then object_name(t1.resource_associated_entity_id)

WHEN 'DATABASE' then ' '

ELSE (select object_name(object_id)

from sys.partitions

where hobt_id=resource_associated_entity_id)

END) as objname,

t1.resource_description as description,

t1.request_mode as mode,

t1.request_status as status,

t2.blocking_session_id

from sys.dm_tran_locks as t1 left outer join sys.dm_os_waiting_tasks as t2

ON t1.lock_owner_address = t2.resource_address

Another interesting aspect is that if I rollback the transaction involving the table variable earlier, the data in the table variable is not rolled back.

Rollback

– this query will return 100 for table variable but 0 for #table.

SELECT COUNT(*) FROM @tv_target

· Fourth, the operations done on table variable are not logged. Here is the example I tried

– create a table variable, insert bunch of rows and update

DECLARE @tv_target TABLE (c11 int, c22 char(100))

INSERT INTO @tv_target (c11, c22)

SELECT c1, c2

FROM tv_source

– update all the rows

update @tv_target set c22 = replicate ('b', 100)

– look at the top 10 log records. I get no records for this case

select top 10 operation,context, [log record fixed length], [log record length], AllocUnitId, AllocUnitName

from fn_dblog(null, null)

where AllocUnitName like '%tv_target%'

order by [Log Record Length] Desc

– create a local temptable

drop table #tv_target

go

create table #tv_target (c11 int, c22 char(100))

go

INSERT INTO #tv_target (c11, c22)

SELECT c1, c2

FROM tv_source

– update all the rows

update #tv_target set c22 = replicate ('b', 100)

– look at the log records. Here I get 100 log records for update

select operation,context, [log record fixed length], [log record length], AllocUnitName

from fn_dblog(null, null)

where AllocUnitName like '%tv_target%'

order by [Log Record Length] Desc

· Fifth, no DDL is allowed on table variables. So if you have a large rowset which needs to be queried often, you may want to use #table when possible so that you can create appropriate indexes. You can get around this by creating unique constraints when declaring table variable.

· Finally, no statistics is maintained on table variable which means that any changes in data impacting table variable will not cause recompilation of queries accessing table variable.

according to this blog table variable consumes double size then temp table.

Plz make me happy with some usefull advice.

Thanks & Regards
Pramod sharma

I have a rule of thumb that you should use what ever tool is best for the job.

In this case temp tables or table variables.

When having to run a ‘while’ loop or having to rerun the query many times, OR if I need to create a rank in a set of data the Table variable is best as you can program your SQL to run like you would run a data set in code, you have no need to have to keep dropping the table (which is always annoying), and you can use a quick ID identity field in the table variable create script that can give you a handy rank, rownumber or sequence number.

Use Temp tables for all else and don’t forget the temp table has the global option which is very useful too when having two connections open and running multiple tests at the same time.

When putting together the design in the first place you may find that creating a non temporary static table is always the best option, maybe developers get too hung up on leaving the workings out in the database, when in fact it makes debugging and picking up other peoples development far easier and you can index in the normal fashion improving performance.

Regards

Darren Harvey
BI Dude MCTS, MCITP, MCDBA

But it does not show me the table variables created in tempdb.

How can I get the list of table variables created in tempdb?

Is it possible in SQL server 2008 or 2005.

Please give me solution.

I think u r missing table name in the last..
It shud be:

SELECT TOP 3000 ROW_NUMBER() OVER (ORDER BY name) from TEST

SELECT TOP 3000 ROW_NUMBER() OVER(ORDER BY a.name)

gives error like

‘ROW_NUMBER’ is not a recognized function name.
when i run ito SQL 2005

Please can u tell me function for gettin rowno in
MS-SQL-2005 or 2008

Table variables performs good only for small resordset. Because there data statistics is not used while creating the execution plan and because of that sometimes fully optimized plan are not created.
Table variable should be used where they are joined with small tables only.

There are many more details which are associated with table variables but this is just one line answer here.

Regards,
Pinal Dave

alter procedure sp_Insert
(
@vStr varchar(max)
)
as

Begin

Declare @GetLine varchar(max), @GetCol varchar(max)
Declare @p int, @col1 varchar(30), @col2 varchar(30)

– Select @maxid = max(InvID) from tblMaster1
– Delete from tblDetail1 where lid = @maxid

create table #temp1 (col1 varchar(20), col2 varchar(20))

While (len(@vstr) !=0)
Begin
if (len(@vstr) !=0 and charindex(‘^^’,@vstr,0) = 0)
Begin
set @getline = @vstr
set @vstr = ”
End
else
Begin
Select @getline = substring(@vstr,0,charindex(‘^^’,@vstr,0))
End

set @p = 0

While (len(@getline)!=0)
Begin
if (len(@getline) !=0 and charindex(‘^’,@getline,0) = 0)
Begin
set @getcol=@getline
set @getline=”

End
Else
Begin
print @getline
Select @getCol = substring(@getline,0,charindex(‘^’,@getline,0))
print @getcol

End
set @P=@P+1
IF(@p=1)
begin

set @col1= @getcol

end

if (@p=2)
begin
set @col2= @getcol

end
Set @getline = substring(@getline , charindex(‘^’ ,@getline,0)+1, len(@getline))
print @getline
End

– Select @maxid= isnull(max(lid) from tbldet
insert into #temp1 values(@col1,@col2)

Set @vstr = substring(@vstr,charindex(‘^^’,@vstr,0)+2 , len(@vstr))

End

Select * from #temp1

End

Ramdas has also give very good comment and very good explanation.

In case of large amount of data temp table is advised because sql server creates, maintains and uses the statistics of temp table while generating the execution plan. Besides this we can create index in tenp tables if that is needed.

Regards,
Pinal Dave

Thank you

Thanks for the explanation. Have couple of questions haunting me now:

1. If both reside in tempDB, how are table variables different from temp tables? What is the advantage of using table variables in place of temp tables?
2. Why is it adviced to go for temporary tables when there is huge amount of data being stored in table variables?

Request you to throw some light on this to make things more clear which would help us in better understanding on each of these at concept and usability level.

Thanks for all your knowledge sharing.

Regards,
Phani.

What matters is from 0 to 6 and 6 to 12 so in fact I am talking about they have same difference.