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Check if a temporary table exists and delete if it exists before creating a temporary table


Question

I am using the following code to check if the temporary table exists and drop the table if it exists before creating again. It works fine as long as I don't change the columns. If I add a column later, it will give an error saying "invalid column". Please let me know what I am doing wrong.

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

CREATE TABLE #Results
(
    Company                CHAR(3),
    StepId                TINYINT,
    FieldId                TINYINT,
)

select company, stepid, fieldid from #Results

--Works fine to this point

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

CREATE TABLE #Results
(
    Company                CHAR(3),
    StepId                TINYINT,
    FieldId                TINYINT,
    NewColumn            NVARCHAR(50)
)

select company, stepid, fieldid, NewColumn from #Results

--Does not work
2016/12/06
1
677
12/6/2016 7:53:40 PM


The statement should be of the order

  1. Alter statement for the table
  2. GO
  3. Select statement.

Without 'GO' in between, the whole thing will be considered as one single script and when the select statement looks for the column,it won't be found.

With 'GO' , it will consider the part of the script up to 'GO' as one single batch and will execute before getting into the query after 'GO'.

2011/08/25

Instead of dropping and re-creating the temp table you can truncate and reuse it

IF OBJECT_ID('tempdb..#Results') IS NOT NULL
    Truncate TABLE #Results
else
    CREATE TABLE #Results
    (
        Company             CHAR(3),
        StepId              TINYINT,
        FieldId             TINYINT,
    )

If you are using Sql Server 2016 or Azure Sql Database then use the below syntax to drop the temp table and recreate it. More info here MSDN

Syntax

DROP TABLE [ IF EXISTS ] [ database_name . [ schema_name ] . | schema_name . ] table_name [ ,...n ]

Query:

DROP TABLE IF EXISTS tempdb.dbo.#Results
CREATE TABLE #Results
  (
   Company             CHAR(3),
   StepId              TINYINT,
   FieldId             TINYINT,
  )
2016/02/13

I think the problem is you need to add GO statement in between to separate the execution into batches. As the second drop script i.e. IF OBJECT_ID('tempdb..#Results') IS NOT NULL DROP TABLE #Results did not drop the temp table being part of single batch. Can you please try the below script.

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

CREATE TABLE #Results
(
    Company                CHAR(3),
    StepId                TINYINT,
    FieldId                TINYINT,
)

GO

select company, stepid, fieldid from #Results

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

CREATE TABLE #Results
(
    Company                CHAR(3),
    StepId                TINYINT,
    FieldId                TINYINT,
    NewColumn            NVARCHAR(50)
)

GO

select company, stepid, fieldid, NewColumn from #Results
2017/07/12

This could be accomplished with a single line of code:

IF OBJECT_ID('tempdb..#tempTableName') IS NOT NULL DROP TABLE #tempTableName;   
2019/04/27

This worked for me: social.msdn.microsoft.com/Forums/en/transactsql/thread/02c6da90-954d-487d-a823-e24b891ec1b0?prof=required

if exists (
    select  * from tempdb.dbo.sysobjects o
    where o.xtype in ('U') 

   and o.id = object_id(N'tempdb..#tempTable')
)
DROP TABLE #tempTable;
2012/10/26

Source: https://stackoverflow.com/questions/659051
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