Firstly, you are setting msg.topic but have the SQL node set to use the internal SQL editor.
Secondly, you should use parameters for this. Especially for dates & times as getting the correct format date string is often difficult.
The better way to do a request is enter the SQL in the mssql node & use parameters
Example..
SELECT * FROM [Dev].[dbo].[MQTTData]
WHERE
Timestamp BETWEEN (@startDate AND @endDate)
where @startDate & @endDate are entered in the "parameters" section & mapped to the correct property in the msg and set for the intended type.
Here is a previous working example
