Outer Joins Graphically
Outer Joins
If English and French both have a unique key on the “ordinal_id” then it’s basically one-to-one relationship We add an arrow in the middle of the line to denote “outer join”. The arrow points from the table that drives the join, ie all the rows in the table pointed from are returned even if a match isn’t found in the table pointed to.
idea for the above graphic came from http://blog.mclaughlinsoftware.com/wp-content/uploads/2009/02/joinmapping.png which was originally posted on http://blog.mclaughlinsoftware.com/oracle-sql-programming/basic-sql-join-semantics/
typeANSIANSI 89 (Oracle)typetypeinner joinenglish INNER JOIN french using (ordinal_id)english e, french f where e.ordinal_id=f.ordinal_id