I have created one stored procedure with 7 temporary tables and each temp table is dropped at the end of their own work.
I am calling the SP from one web service and same web service we are used for different instance.
I have dropped every temp table forcefully but when SP executes it will not delete any of the temporary table which are located in "tempdb/Temporary Table". And, when I open new instance of my application and try to execute same SP it will modify same temp tables.
This creates problem for me. it will lock the tables when SP execute simultaneously it will lock the table and my sp is not able to produce result and throw exception.
So I want to drop my temporary tables at the end of my operation. please help.
I can't tell you why this is happening, but I have dealt with it before as well.
Try cleaning up your tables at the beginning or end of the SP or using table variables.
IF object_id('tempdb..#TableName') IS NOT NULL DROP TABLE #TableName
This can occur in case if you have used many Temp tables and you have some Error in between of Your sp and your drop statement could not executed.
So its always best practice to use
IF object_id('tempdb..#TableName') IS NOT NULL DROP TABLE #TableName
in start of SP.
To force dropping of temp tables use
BEGIN TRY DROP #MyTable END TRY BEGIN CATCH END CATCH
Ugly but effective. Use a separate TRY for each temporary table.
IF object_id('tempdb..#TableName') IS NOT NULL DROP TABLE #TableName
I think this will not work as we know sql server store temp table name with adding some extra character.
if exists(select 1 from tempdb.sys.tables where name like '#TableName%')
DROP TABLE #TableName
Related
I have a table called myTable where continuous insertion is happening. I will rename that table by myTable_Date and create a new table, myTable through a Store Procedure.
I want to know what will happen during re-naming and re-creating the table, will it drop any packet?
SQL Server has sp_rename built in if you just want to change the name of a table.
sp_rename myTable, myTable_Date
Would change the name from myTable to myTable_Date
But it only changes the name reference in sys.Objects so make sure any references are altered and read the documentation about it :)
The Microsoft doc for it is HERE
When you rename the myTable to myTableDate, myTable won't exist anymore so if someone tries to insert something inside myTable it will fail.
When you create new myTable with the same name and columns everything will be fine and the insertion process will continue.
I suggest you to make a little script renaming the table and creating new one. Something like this:
sp_rename myTable, myTable_Date
GO
CREATE TABLE myTable(
-- Table definition
)
When you rename the table you will get warning like this: "Caution: Changing any part of an object name could break scripts and stored procedures." so you better create the new table fast.
Other option is you create a table exact like myTable and insert all data from myTable there and then can delete them from myTable. No renaming, no dropping and insertion process will not be interrupted.
I want to know what will happen during re-naming and re-creating the
table, will it drop any packet?
Inserts attempted after the table is renamed will err until the table is recreated. You can avoid that by executing the tasks in a transaction. Short term blocking will happen if an insert is attempted before the transaction is committed but no rows will be lost. For example:
CREATE PROC dbo.ReanmeMytableWithDate
AS
DECLARE #NewName sysname = 'mytable_' + CONVERT(nchar(8), SYSDATETIME(), 112);
SET XACT_ABORT ON;
BEGIN TRY;
BEGIN TRAN;
EXEC sp_rename N'dbo.mytable', #NewName;
CREATE TABLE dbo.mytable(
col1 int
);
COMMIT;
END TRY
BEGIN CATCH
THROW;
END CATCH;
GO
I don't know your use case for renaming tables like this but it seems table partitioning might be a better approach as #Damien_The_Unbeliever suggested. Although table partitioning previously required Enterprise Edition, the feature is available in Standard Edition beginning with SQL Server 2016 SP1 as well as Azure SQL Database.
I need to create a table, with many indexes that is scoped only to the running sproc.
I tried a table variable, but this doesn't seem to support indexes. A local temp table seems to create a 'real' table, and need to be explicitly dropped at the end of the proc, from which I'm inferring that it's also shared across concurrent runs and so would break.
What can I use to store data with indexes that is scoped only to the indicidual instance of the running sproc?
You don't need to worry about dropping the table. SQL Server does that automatically. As explained in the documentation:
A local temporary table created in a stored procedure is dropped automatically when the stored procedure is finished. The table can be
referenced by any nested stored procedures executed by the stored
procedure that created the table. The table cannot be referenced by
the process that called the stored procedure that created the table.
This is a result of the scoping rules for access to the temporary table.
I will admit, that in practice, I tend to explicitly drop temporary tables in stored procedures. The differences among:
create table temp
create table #temp
create table ##temp
are all too similar to rely on the fact that the second is dropped automatically, but the first and third are not. However, this is my "problem" and not a best practice.
Updated
The answer is don't worry at all since the temp table will be as if it was a local variable inside the stored procedure.
I wanted to make sure if the doubt I had was correct or not, so I made this test
create procedure TestTempData
as
begin
declare #date datetime = getdate()
if object_id('#testing') is not null
drop table #testing
create table #testing(
Id int identity(1,1),
[Date] datetime
)
print 'run at ' + format(#date,'HH:mm:ss')
insert into #testing([Date]) values
(dateadd(second,10,getdate())),
(dateadd(second,20,getdate())),
(dateadd(second,30,getdate()))
waitfor delay '00:00:15'
select * from #testing
end
then I ran this query
exec TestTempData
waitfor delay '00:00:02'
exec TestTempData
the result came as
run at 14:57:39
Id Date
1 2016-09-21 14:57:49.117
2 2016-09-21 14:57:59.117
3 2016-09-21 14:58:09.117
the second result
run at 14:57:56
Id Date
1 2016-09-21 14:58:06.113
2 2016-09-21 14:58:16.113
3 2016-09-21 14:58:26.113
If the concurrent runs will effect the #temp table, both results
should be the same which was not the case, It seems that the temp
table inside stored procedure acts like a local variable inside a
method.
Before chatting with Gordon Linoff
Since you mentioned that the temp table is shared across concurrent runs, your temp table should be unique for the current run.
Your stored procedure should look like this
create procedure YourProc(#userId int)
as
begin
if object_id('#temp' + #userId) IS NOT NULL
execute( 'DROP TABLE #temp' + #userId +'')
...
execute('insert into #temp' + #userId + 'values(...')
end
The above solution will ensure that no conflict will occur and no data will be lost since each execution will be unique per userId
you don't need to drop the table when you finish because it will be dropped automatically by it self
Hope this will help you
I want to pass a temp table from one execution path to another one nested in side it
What I have tried is this:
DECLARE #SQLQuery AS NVARCHAR(MAX)
SET #SQLQuery = '
--populate #tempTable with values
EXECUTE('SELECT TOP (100) * FROM ' + tempdb..#tempTable)
EXECUTE sp_executesql #SQLQuery
but it fails with this error message:
Incorrect syntax near 'tempdb'
Is there a another\better way to pass temporary table between execution contexts?
You can create a global temp table using the ##tablename syntax (double hash). The difference is explained on the TechNet site:
There are two types of temporary tables: local and global. They differ from each other in their names, their visibility, and their availability. Local temporary tables have a single number sign (#) as the first character of their names; they are visible only to the current connection for the user, and they are deleted when the user disconnects from the instance of SQL Server. Global temporary tables have two number signs (##) as the first characters of their names; they are visible to any user after they are created, and they are deleted when all users referencing the table disconnect from the instance of SQL Server.
For example, if you create the table employees, the table can be used by any person who has the security permissions in the database to use it, until the table is deleted. If a database session creates the local temporary table #employees, only the session can work with the table, and it is deleted when the session disconnects. If you create the global temporary table ##employees, any user in the database can work with this table. If no other user works with this table after you create it, the table is deleted when you disconnect. If another user works with the table after you create it, SQL Server deletes it after you disconnect and after all other sessions are no longer actively using it.
If a temporary table is created with a named constraint and the temporary table is created within the scope of a user-defined transaction, only one user at a time can execute the statement that creates the temp table. For example, if a stored procedure creates a temporary table with a named primary key constraint, the stored procedure cannot be executed simultaneously by multiple users.
The next suggestion may be even more helpful:
Many uses of temporary tables can be replaced with variables that have the table data type. For more information about using table variables, see table (Transact-SQL).
Your temp table will be visible inside the dynamic sql with no problem. I am not sure if you are creating the temp table inside the dynamic sql or before.
Here it is with the table created BEFORE the dynamic sql.
create table #Temp(SomeValue varchar(10))
insert #Temp select 'made it'
exec sp_executesql N'select * from #Temp'
The reason for your syntax error is that you are doing an unnecessary EXECUTE inside an EXECUTE, and you didn't escape the nested single-quote. This would be the correct way to write it:
SET #SQLQuery='
--populate #tempTable with values
SELECT TOP 100 * FROM tempdb..#tempTable'
However, I have a feeling that the syntax error is only the beginning of your problems. Impossible to tell what you're ultimately trying to do here, only seeing this much of the code, though.
Your quotations are messed up. Try:
SET #SQLQuery='
--populate #tempTable with values
EXECUTE(''SELECT TOP 100 * FROM '' + tempdb..#tempTable + '') '
I know we will have to drop the table manually after using create table, but how about select into #temp ? will it be cleaned up at the end of the the stored proc? thanks
Better late than never, I suppose. In case other people have trouble finding the documentation:
A local temporary table created in a stored procedure is dropped
automatically when the stored procedure is finished.
I was wondering how / if it's possible to have a query which drops all temporary tables?
I've been trying to work something out using the tempdb.sys.tables, but am struggling to format the name column to make it something that can then be dropped - another factor making things a bit trickier is that often the temp table names contain a '_' which means doing a replace becomes a bit more fiddly (for me at least!)
Is there anything I can use that will drop all temp tables (local or global) without having to drop them all individually on a named basis?
Thanks!
The point of temporary tables is that they are.. temporary. As soon as they go out of scope
#temp create in stored proc : stored proc exits
#temp created in session : session disconnects
##temp : session that created it disconnects
The query disappears. If you find that you need to remove temporary tables manually, you need to revisit how you are using them.
For the global ones, this will generate and execute the statement to drop them all.
declare #sql nvarchar(max)
select #sql = isnull(#sql+';', '') + 'drop table ' + quotename(name)
from tempdb..sysobjects
where name like '##%'
exec (#sql)
It is a bad idea to drop other sessions' [global] temp tables though.
For the local (to this session) temp tables, just disconnect and reconnect again.
The version below avoids all of the hassles of dealing with the '_'s. I just wanted to get rid of non-global temp tables, hence the '#[^#]%' in my WHERE clause, drop the [^#] if you want to drop global temp tables as well, or use a '##%' if you only want to drop global temp tables.
The DROP statement seems happy to take the full name with the '_', etc., so we don't need to manipulate and edit these. The OBJECT_ID(...) NOT NULL allows me to avoid tables that were not created by my session, presumably since these tables should not be 'visible' to me, they come back with NULL from this call. The QUOTENAME is needed to make sure the name is correctly quoted / escaped. If you have no temp tables, #d_sql will be the empty string still, so we check for that before printing / executing.
DECLARE #d_sql NVARCHAR(MAX)
SET #d_sql = ''
SELECT #d_sql = #d_sql + 'DROP TABLE ' + QUOTENAME(name) + ';
'
FROM tempdb..sysobjects
WHERE name like '#[^#]%'
AND OBJECT_ID('tempdb..'+QUOTENAME(name)) IS NOT NULL
IF #d_sql <> ''
BEGIN
PRINT #d_sql
-- EXEC( #d_sql )
END
In a stored procedure they are dropped automatically when the execution of the proc completes.
I normally come across the desire for this when I copy code out of a stored procedure to debug part of it and the stored proc does not contain the drop table commands.
Closing and reopening the connection works as stated in the accepted answer. Rather than doing this manually after each execution you can enable SQLCMD mode on the Query menu in SSMS
And then use the :connect command (adjust to your server/instance name)
:connect (local)\SQL2014
create table #foo(x int)
create table #bar(x int)
select *
from #foo
Can be run multiple times without problems. The messages tab shows
Connecting to (local)\SQL2014...
(0 row(s) affected)
Disconnecting connection from (local)\SQL2014...