Difference between revisions of "Non-Equality Joins"
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'''match, you can use a non-equality join to determine whether the item being shipped''' | '''match, you can use a non-equality join to determine whether the item being shipped''' | ||
'''falls between minimum and maximum ranges in the columns.''' | '''falls between minimum and maximum ranges in the columns.''' | ||
== Traditional Non-Equality JOIN === | |||
SELECT b.title, p.gift | |||
FROM books b, promotion p | |||
WHERE b.retail BETWEEN p.minretail AND p.maxretail; | |||
=== Non-Equality Joins: JOIN Method === | |||
[[#Select Command|Back To Top]]-[[Main_Page| Home]] - [[Oracle_SQL|Category]] | [[#Select Command|Back To Top]]-[[Main_Page| Home]] - [[Oracle_SQL|Category]] | ||
Revision as of 23:18, 23 October 2017
With an equality join, the data value of a record stored in the common column for the first table must match the data value in the second table. However, in many cases, there’s no exact match. A non-equality join is used when the related columns can’t be joined with an equal sign—meaning there are no equivalent rows in the tables to be joined.
A non-equality join enables you to store a range’s minimum value in one column of a record and the maximum value in another column. So instead of finding a column-to column match, you can use a non-equality join to determine whether the item being shipped falls between minimum and maximum ranges in the columns.
Traditional Non-Equality JOIN =
SELECT b.title, p.gift FROM books b, promotion p WHERE b.retail BETWEEN p.minretail AND p.maxretail;