Progressive queries

Count the people in the Sales department; how many of them live in Beijing; and how many of those living in Beijing are female.

SQL

To count the people in the Sales department:

SELECT count(*) FROM employee WHERE dept='Sales'

To count how many of them live in Beijing.

SELECT count(*) FROM employee
WHERE dept='Sales' AND domicile='beijing'

To count how many of those living in Beijing are female.

SELECT count(*) FROM employee
WHERE dept='Sales' AND domicile='beijing' AND gender='female'

You can’t perform a SQL computation through several query calls, so the user needs to write the condition repeatedly in a progressive query. It is tedious and inefficient.

SPL

	A	B
1	=demo.query("select * from employee").select(dept:"sales")	=A1.len()
2	=A1.select(domicile:"beijing")	=A2.len()
3	=A2.select(gender:"female")	=A3.len()

SPL supports using record sets as variable values, enabling users to make the progressive query step by step.