Pass temp table to EXEC sp_executesql - sql

Question

How can I pass temp table (#table) to EXEC sp_executesql #query
set #query = 'SELECT GsName, ' + #cols + ' from
(
select GSName, [THour], NumOfTransactions
from #table
) x
pivot
(
max([NumOfTransactions])
for [THour] in (' + #cols + ')
) p '

Answer 1

What you have here is not Temporary Table, but a Table-Valued Parameter.
Table-valued parameters are declared by using user-defined table
types. You can use table-valued parameters to send multiple rows of
data to a Transact-SQL statement or a routine, such as a stored
procedure or function, without creating a temporary table or many
parameters.
sp_executesql does support table-valued parameters, but they must be of declared type.
-- So, first we must declare User-Defined Table Type
CREATE TYPE udtYB_Test AS TABLE(GSName nvarchar(100), THour time, NumOfTransactions int);
GO
-- Now we can create Table-Valued Parameter
Declare #table udtYB_Test;
-- And store there some data
Insert Into #table (GSName, THour, NumOfTransactions)
Values ('Sample', SYSUTCDATETIME(), 1);
-- Just for the reference
Select * From #table;
-- To pass variable to sp_executesql we need parameters definition
DECLARE #ParmDefinition nvarchar(500) = N'#table udtYB_Test READONLY';
-- Please note: table-valued parameter must be READONLY
-- Here I use simplified query for demonstration only
DECLARE #query nvarchar(500) = 'SELECT * FROM #table';
-- and the result should be identical to the reference above
EXECUTE sp_executesql #query, #ParmDefinition, #table = #table;
-- User-Defined Table Type cleanup
DROP TYPE udtYB_Test;
GO
In most practical cases it is much easier to use a temporary table:
Create Table #table (GSName nvarchar(100), THour time, NumOfTransactions int);
Insert Into #table (GSName, THour, NumOfTransactions) Values ('Sample', SYSUTCDATETIME(), 1);
Select * From #table;
DECLARE #query nvarchar(500) = 'SELECT * FROM #table';
EXECUTE sp_executesql #query;
Drop Table #table;