How to declare temponary/variable table with a dynamic number of column - sql

Question

I have table like this:
Table Name|Number of columns
How to dynamically create temporary tables inside stored procedure with names from first table, and variable columns named e.g. col1, col2, etc..
I also need to insert values to them and make another logic on them.
Example:
Table1|3
Table1(col1 nvarchar(max), col2 nvarchar(max), col3 nvarchar(max))

Answer 1

You will need to use dynamic sql like below:
declare #counter int = 1
declare #numberOfCols int = 3 -- OR you can use ->(select numberofcolumns from firsttable)
declare #dynamic nvarchar(max) = ''
declare #sql nvarchar(max) = 'CREATE TABLE #TEMP (';
while #counter <= #numberofCols
begin
set #dynamic = #dynamic + 'col'+cast(#counter as nvarchar(5))+' nvarchar(max) ';
if(#counter <> #numberOfCols)
begin
set #dynamic = #dynamic + ', ';
end
set #counter = #counter + 1
end
set #sql = #sql + #dynamic + ') select * from #temp'
select #sql
EXECUTE sp_executesql #sql

Answer 2

I have created a stored procedure regarding your question. I wish it can help you.
ALTER PROCEDURE P_ProcedureName
#NumberOfColumns INT=2 --expected 1 or more column
AS
DECLARE #SQLString VARCHAR(MAX)=''
DECLARE #Seq INT=2
IF #NumberOfColumns=0
BEGIN
SELECT 'Please add valid number of column'
RETURN
END
CREATE TABLE #Table
(
Id INT NOT NULL IDENTITY(1,1)
,Column1 VARCHAR(MAX)
)
WHILE #Seq<=#NumberOfColumns
BEGIN
SET #SQLString=#SQLString+'ALTER TABLE #Table ADD Column'+CAST(#Seq AS VARCHAR)+' VARCHAR(MAX)'+char(13)
PRINT(#SQLString)
SET #Seq +=1
END
EXEC(#SQLString)
SELECT * FROM #Table
GO
P_ProcedureName 5