Why is the temporary table not dynamically created in the procedure?

Question

SQL Server

The stored procedure dynamically creates columns in a temporary table. On the first run a column named "Column1" is created, on the next run "Column2" , i.e. column name - calculated.

EXEC _test1 'column1'
EXEC _test1 'column2'
EXEC _test1 'column3'

But in fact, on the second and third hits, the table shows the 'column1' column - even if I open a new SSMS window or start a new instance of SSMS .

dbo._test1

CREATE procedure dbo._test1(
  @name varchar( 32)
)
AS 
BEGIN
  Select SPID = @@SPID

  if object_id('tempdb..#TST') is not null				Select  'temp table #TST exists on start'

  Create table #TST(	dummy varchar(32) NULL	)

  Select *  from #tst

Declare @SQLString varchar(255)
  SET @SQLString = 'ALTER  TABLE #TST add [' + @name +  '] varchar(255) null '
  EXEC ( @SQLString )

  Select *  from #tst

  drop table #TST

  if object_id('tempdb..#TST') is not null			Select  'temp table #TST exists on STOP'
END

It is completely unclear where the old column name appears in the temporary table when the "second" call comes from? On older 2000 - 2014 versions of SQL, this problem did not occur. The problem manifests itself on Microsoft SQL Server 2019.

Answer 1

SELECT @@VERSION
GO
EXEC _test1 'column1'
GO
EXEC _test1 'column2'
GO
EXEC _test1 'column3'
GO

Result

Microsoft SQL Server 2019 (RTM-CU14) (KB5007182) - 15.0.4188.2 (X64) 

(затронута одна строка)

SPID
------
60

(затронута одна строка)

dummy
--------------------------------

(затронуто строк: 0)

dummy                            column1
-------------------------------- ---------

(затронуто строк: 0)

SPID
------
60

(затронута одна строка)

dummy
--------------------------------

(затронуто строк: 0)

dummy                            column2
-------------------------------- ---------

(затронуто строк: 0)

SPID
------
60

(затронута одна строка)

dummy
--------------------------------

(затронуто строк: 0)

dummy                            column3
-------------------------------- ---------

(затронуто строк: 0)


Время выполнения: 2022-01-18T13:20:25.1207006+03:00

Answer 2

Problem solved.
Cumulative update CU14 installed
SQL version updated to
Microsoft SQL Server 2019 (RTM-CU14) (KB5007182) - 15.0.4188.2 (X64) Nov 3 2021 19:19:51 Copyright (C) 2019 Microsoft Corporation Standard Edition (64-bit) on Windows 10 Enterprise 10.0 (Build 19042: )
Thanks for the tip.