SQL Reference Volume 1 - Ibm

Examples of joinsSELECT * FROM J1, J2 WHERE W=YThe following left outer join will get back the missing row from J1 with nulls forthe columns of J2. Every row from J1 is included.SELECT * FROM J1 LEFT OUTER JOIN J2 ON W=YW X Y Z--- ------ --- ------A 11 A 21B 12 - -C 13 C 22The following right outer join will get back the missing row from J2 with nulls forthe columns of J1. Every row from J2 is included.SELECT * FROM J1 RIGHT OUTER JOIN J2 ON W=YW X Y Z--- ------ --- ------A 11 A 21C 13 C 22- - D 23The following full outer join will get back the missing rows from both J1 and J2with nulls where appropriate. Every row from both J1 and J2 is included.SELECT * FROM J1 FULL OUTER JOIN J2 ON W=YW X Y Z--- ------ --- ------A 11 A 21C 13 C 22- - D 23B 12 - -Example B2: Using the tables J1 and J2 from the previous example, examine whathappens when and additional predicate is added to the search condition.SELECT * FROM J1 INNER JOIN J2 ON W=Y AND X=13W X Y Z--- ------ --- ------C 13 C 22The additional condition caused the inner join to select only 1 row compared to theinner join in “Example B1” on page 532.Notice what the impact of this is on the full outer join.SELECT * FROM J1 FULL OUTER JOIN J2 ON W=Y AND X=13W X Y Z--- ------ --- ------- - A 21C 13 C 22- - D 23A 11 - -B 12 - -The result now has 5 rows (compared to 4 without the additional predicate) sincethere was only 1 row in the inner join and all rows of both tables must bereturned.Chapter 5. Queries 533