Execute stored procedure with inputs from SELECT

declare @var1 int, @var2 int, @var3 int, @var4 int

select @var1=var1, @var2=var2, @var3=var3, @var4=var4 from SPInputs

exec sp_TestSP @var1, @var2, @var3, @var4

>Is there a way to execute a stored procedure using the results from a select?
not like that.
how many rows do you get?

so either, you get the procedure into a function, or, if your query returns only 1 row, or you need to do a cursor on the SELECT.

No.  You could modify the sp to process data from a temp table, load the temp table prior to calling the sp, then passing a flag to the stored proc to let it know to process the value in the temp table rather than in the params.  For example:

CREATE TABLE #params (
    var1 VARCHAR(30),
    var2 INT,
    var3 INT,
    var4 DATETIME
    )
INSERT INTO #params
SELECT var1, var2, var3, var4
FROM SPInputs

EXEC sp_TestSP 'UseTemp', -1

If I made it a table-valued UDF, how would I join to it?   Basically, the select can return multiple rows, and each of those rows contains variables that should be passed into the function.  In addition, the function will return multiple rows.  So if the function returns 3 rows per call and the SPInputs table has 2 rows, the SELECT would return a ResultSet of 6 rows...

      SELECT *
      FROM fn_ResultSet(spi.var1, spi.var2, spi.var3, spi.var4)
      CROSS JOIN SPInputs spi