conditional add clause

[jimfog]

take a look at this query...it has a series of AND clasues..pay attention to the 3rd commented..it sums up what I want to do.

SELECT lastname,city FROM users
INNER JOIN business_users
 ON business_users.user_ID=users.user_ID 
WHERE   users.active=1  
AND business_users.sched_entered =1 
AND business_users.services_entered=1
--and  business.users.staff_entered=1 only if business.users.sraff_enfaged_in_appt=1
 AND lastname LIKE  'p%';

I want to ask as prerequisite business.users.staff_entered ONLY if business.users.sraff_enfaged_in_appt column is true.

How I would go about achieving that?

[Ingolme]

You just need to break that down into its logical components.

If you only want to test that field X is 1 when field Y is 1, it's like always returning true when field Y is 0 and only sometimes returning true when field Y is 1.

The result would look like this:

AND (
  Y = 0 /* Value of field X does not matter when Y is 0 */
  OR
  Y = 1 AND X = 1 /* Value of field X matters when Y is 1 */
)

 

[jimfog]

that did,,,not used to in applying the rules of logic in sql...probably you might say that they no differ from other languages and you would be right....anyway..tnanks.