Dynamic SQL stored procedure not populating temporary table - sql

Question

I am using a stored procedure with one parameter (#tablename) to generate a table of attributes about the table named via the parameter.
I call the stored procedure as follows
EXEC sp_Schema_Presentation #tablename = 'UserID'
And run the stored procedure (at the bottom of this post).
I have created a #DynamicSQL string in order to use my #tablename parameter. However, the SELECT statement, in which it's used, also creates the #TEMP table.
The rest of the query uses this #TEMP table so I DECLARE its structure at the top.
However, when I run the stored procedure, the #TEMP table is empty
If I hard code the #tablename, the query will work. Any ideas how I can fix this?
Thanks
CREATE TABLE #TEMP
(
SampleKey nvarchar(MAX),
SampleData nvarchar(MAX)
)
DECLARE #DynamicSQL NVARCHAR(MAX)
SET #DynamicSQL = N'SELECT B.*
INTO dbo.#TEMP
FROM (
SELECT * FROM ' + #Tablename + N' ORDER BY 1 DESC
OFFSET 1 ROWS
FETCH NEXT 1 ROWS ONLY
) A
CROSS APPLY (
SELECT [Key] AS SampleKey
,Value AS SampleData
FROM OpenJson( (SELECT A.* FOR JSON Path, Without_Array_Wrapper,INCLUDE_NULL_VALUES ) )
) B'
Full stored procedure in SQL Server 2016:
ALTER PROCEDURE [dbo].[sp_Schema_Presentation]
#TableName nvarchar(MAX)
AS
BEGIN
CREATE TABLE #TEMP
(
SampleKey nvarchar(MAX),
SampleData nvarchar(MAX)
)
DECLARE #DynamicSQL NVARCHAR(MAX)
SET #DynamicSQL = N'SELECT B.*
INTO dbo.#TEMP
FROM (
SELECT * FROM ' + #Tablename + N' ORDER BY 1 DESC
OFFSET 1 ROWS
FETCH NEXT 1 ROWS ONLY
) A
CROSS APPLY (
SELECT [Key] AS SampleKey
,Value AS SampleData
FROM OpenJson( (SELECT A.* FOR JSON Path, Without_Array_Wrapper,INCLUDE_NULL_VALUES ) )
) B'
DECLARE #Columns as NVARCHAR(MAX)
SELECT #Columns = COALESCE(#Columns + ', ','') + QUOTENAME(COLUMN_NAME)
FROM
(
SELECT COLUMN_NAME FROM PRESENTATION_PP.INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = N''' + #TableName + '''
) AS B
EXECUTE sp_executesql #DynamicSQL
SELECT a.COLUMN_NAME,
CASE WHEN a.COLUMN_NAME LIKE '%[_]_key' THEN a.COLUMN_NAME
ELSE REPLACE(a.COLUMN_NAME,'_',' ') END AS DISPLAY_NAME,
a.DATA_TYPE, COALESCE(a.CHARACTER_MAXIMUM_LENGTH, a.NUMERIC_PRECISION) AS SIZE,
CASE WHEN NUMERIC_SCALE IS NULL THEN 0
ELSE NUMERIC_SCALE END AS SCALE,
a.IS_NULLABLE AS NULLABLE,
CASE WHEN i.is_primary_key IS NOT NULL THEN 'YES'
ELSE 'NO' END AS PK,
#TEMP.SampleData
FROM PRESENTATION_PP.INFORMATION_SCHEMA.COLUMNS a
LEFT JOIN
sys.columns c ON a.COLUMN_NAME = c.name
LEFT JOIN
sys.index_columns ic ON ic.object_id = c.object_id AND ic.column_id = c.column_id
LEFT JOIN
sys.indexes i ON ic.object_id = i.object_id AND ic.index_id = i.index_id
LEFT JOIN
#TEMP ON a.COLUMN_NAME COLLATE SQL_Latin1_General_CP1_CI_AI = #TEMP.SampleKey COLLATE SQL_Latin1_General_CP1_CI_AI
WHERE TABLE_NAME = #TableName AND c.object_id = OBJECT_ID(#TableName)
SELECT * FROM #TEMP
DROP TABLE #TEMP
END

Answer 1

Create the #Temp table first, and then INSERT INTO not Select ... Into #Temp
CREATE TABLE #TEMP (SampleKey nvarchar(MAX), SampleData nvarchar(MAX))
DECLARE #DynamicSQL NVARCHAR(MAX)
SET #DynamicSQL = N'
Insert Into #Temp
SELECT B.*
FROM (
SELECT * FROM ' + #Tablename + N' ORDER BY 1 DESC
OFFSET 1 ROWS
FETCH NEXT 1 ROWS ONLY
) A
CROSS APPLY (
SELECT [Key] AS SampleKey
,Value AS SampleData
FROM OpenJson( (SELECT A.* FOR JSON Path, Without_Array_Wrapper,INCLUDE_NULL_VALUES ) )
) B
'
Exec(#DynamicSQL)
Select * from #Temp