Session temp tables not visible

Question

Session temp tables not visible

river1

SSC-Insane

Points: 24309
More actions
January 25, 2018 at 6:56 am

#410105

Dear all,
I have a drop statement related with a temp table that works properly when called from inside an SP but does not drop anything when callen from inside the query pane (whiout being inside an SP.
Example:
DECLARE @DB VARCHAR(500)
DECLARE @STRSQL VARCHAR(1000)
IF EXISTS (SELECT * FROM SYS.OBJECTS WHERE NAME ='#ReturnDBNames')
BEGIN
DROP TABLE #ReturnDBNames
END
CREATE TABLE #ReturnDBNames
(
Name VARCHAR(200)
)
DECLARE UserDBs CURSOR FOR
SELECT
[d].[name]
FROM
[sys].[databases] AS [d]
WHERE
[d].database_id > 4
ORDER BY
[d].[name]

The DROP, only drops the table if called from inside a SP, can you help me understand why? thank you.

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ChrisM@Work SSC Guru Points: 186127 More actions · Answer 1

Not really - the temp table will be dropped when the stored procedure completes, because this isn't the correct code for identifying whether or not a temp table exists.

DECLARE @DB VARCHAR(500)

DECLARE @STRSQL VARCHAR(1000)

-- IF EXISTS (SELECT * FROM SYS.OBJECTS WHERE NAME ='#ReturnDBNames')

--BEGIN

-- DROP TABLE #ReturnDBNames

--END

IF OBJECT_ID('tempdb..#ReturnDBNames') IS NOT NULL DROP TABLE #ReturnDBNames;

CREATE TABLE #ReturnDBNames (

[Name] VARCHAR(200)

)

^{“Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail Shaw}

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Phil Parkin SSC Guru Points: 246987 More actions · Answer 2

As you're in 2016, you can use DIE syntax:

DROP TABLE IF EXISTS #ReturnDBNames

The absence of evidence is not evidence of absence.
Martin Rees

You can lead a horse to water, but a pencil must be lead.
Stan Laurel

river1 SSC-Insane Points: 24309 More actions · Answer 3

ChrisM@Work - Thursday, January 25, 2018 7:04 AM
Not really - the temp table will be dropped when the stored procedure completes, because this isn't the correct code for identifying whether or not a temp table exists.
DECLARE @DB VARCHAR(500)
DECLARE @STRSQL VARCHAR(1000)
-- IF EXISTS (SELECT * FROM SYS.OBJECTS WHERE NAME ='#ReturnDBNames')
--BEGIN
-- DROP TABLE #ReturnDBNames
--END
IF OBJECT_ID('tempdb..#ReturnDBNames') IS NOT NULL DROP TABLE #ReturnDBNames;
CREATE TABLE #ReturnDBNames (
[Name] VARCHAR(200)
)

🙂 Ok. So in this case is working just because when the SP is droped all its temporary tables will also be droped because the session as ended, is that it?