我如何运行SQL函数QUERY

Question

I have 4 tables

• EMPLOYEE ( E#, NAME ), primary key is E#
• DRIVER ( E#, L# ), primary key is E# references EMPLOYEE
• TRIP ( T#, L# ), primary key is T# , foreign key L# references DRIVER
• TRIPPT ( T#, PT# ) primary key is T# references TRIP

I have create a function that finds the length (total number of pt#) of the longest point perform by the driver

My query so far:

create or replace function LONGPT (DL# in TRIP.L#%type)
   return TRIPPT.PT#%type
IS
   TRIPPT#   TRIPPT.PT#%type;
begin
   select max (PT#)
     into TRIPPT# 
     from TRIPPT
    where T# in (select T#
                   from TRIP
                  where L# = DL#);

   return nvl (TRIPPT#, 0);
end LONGPT;

How can I do a select query to display the NAME of the employee, LONGPT. The driver name that perform no trip point need to be in the query as well.

I have tried:

SELECT DRIVER.L# AS License_No, LONGTPT(TRIP.L#) AS "LONGEST POINT" 
FROM DRIVER 
   LEFT OUTER JOIN TRIP on DRIVER.L# = TRIP.L#;

This only query the L# and the LONGEST Point.

Could anyone guide me how to do the select statement on display the NAME of the employee and with my function LONGPT.

Answer 1

Here is the working query i manage to figure out.

SELECT DISTINCT EMPLOYEE.NAME, LONGPT(TRIP.L#) AS "LONGEST Point"
FROM DRIVER Join EMPLOYEE ON DRIVER.E# = EMPLOYEE.E# LEFT OUTER JOIN 
TRIP on DRIVER.L# = TRIP.L#;