Question

Q:

I have 5 or 6 tables , and i need data from these tables :
i make the following join statement to accomplish my query.

SELECT d.batch_no,d.studytype_code,d.camp_code,d.dep_code,d.start_date,d.end_date,a.year,a.term_code,c.studytype_name ,e.dep_name_ar,f.camp_name_ar
FROM llkbatch a , llkbatch_category b , mm19studytype c ,llkbatch_exception d  ,llkdepartment e,llkcamp f
WHERE   a.batch_no = b.batch_no
AND  b.studytype_code = c.studytype_code 
AND  b.batch_no = d.batch_no
AND b.studytype_code = d.studytype_code 
AND d.dep_code = e.dep_code
AND d.camp_code = f.camp_code

but i think that the join sometimes is less performance way to do things like that,is there any alternative to this in a programming way or in the database layer, i mean alternatives to joins in general and when should i go away from the joins.
thanks a lot.

Answer 1

There is a more modern ANSI join syntax that will make your joins more readable, but it should not affect performance:

SELECT d.batch_no,d.studytype_code,d.camp_code,d.dep_code,d.start_date,d.end_date,
       a.year,a.term_code,c.studytype_name ,e.dep_name_ar,f.camp_name_ar
FROM ra1batch a 
JOIN ra1batch_category b ON a.batch_no = b.batch_no
JOIN ra1studytype c ON b.studytype_code = c.studytype_code
JOIN ra1batch_exception d ON b.batch_no = d.batch_no
                         AND b.studytype_code = d.studytype_code 
JOIN rr1department e ON d.dep_code = e.dep_code
JOIN rr2camp f ON d.camp_code = f.camp_code