Practical SQL Handbook, The: Using SQL Variants, Fourth Edition

Joins Not Based on Equality

Joins not based on equality can be described by their comparison condition, as “less-than join,” “greater-than join,” and so forth. This example of a less-than join displays orders that were shipped on a date later than the sale (the company attempts to ship all orders on the day received):

SQL

select distinct s.sonum, s.stor_id, s.sdate,
 sd.date_shipped
from sales s, salesdetails sd
where s.sdate < sd.date_shipped and s.sonum = sd.sonum sonum stor_id sdate date_shipped =========== ======= ==================== ==================== 1 7066 Sep 13 1998 12:00 am Sep 15 1998 12:00 am 2 7067 Sep 14 1998 12:00 am Sep 15 1998 12:00 am 3 7131 Sep 14 1998 12:00 am Sep 18 1998 12:00 am 4 7131 Sep 14 1998 12:00 am Sep 18 1998 ...