Hi everyone

I'm trying to understand the difference between EXISTS and WHERE...IN in SQL. Some articles that I've read suggest that WHERE...IN subqueries can be re-written as WHERE EXISTS.

I have the following query:

SELECT * FROM Customer, Appointment WHERE Appointment.CustomerCode = Customer.CustomerCode AND Appointment.ServerCode IN (SELECT ServerCode FROM Appointment WHERE CustomerCode = '102');

How would I rewrite this as a query using EXISTS instead of WHERE...IN?

Thanks for any help.

SELECT * FROM Customer, Appointment WHERE Appointment.CustomerCode = Customer.CustomerCode AND EXISTS ( SELECT 'hola' FROM Appointment WHERE ServerCode = Appointment.ServerCode AND CustomerCode = '102');

Wait...that's not ANSI

you talkin' to me? that sql conforms to SQL-2003

please check ANSI compliance for yourself, mister johnny-come-lately, before you dig up another ten-week-old thread to cast asparagus on my sql skillz0rz