This is an example of a Cascading Outer Join. Notice that the salgrade table is outer-joined, even though there is no row in the emp table that does not have a matching row in salgrade. LEFT OUTER JOIN scott.salgrade s ON e.sal BETWEEN s.losal LEFT OUTER JOIN scott.emp e ON d.deptno = e.deptno SALES 30 BLAKE 2850 3000(Notice that the OPERATIONS department is shown, even though it has no employees.) It can save a lot of time and effort, especially with outer joins.įor example, using the pt, emp and sal tables, say we want to show all departments (whether they have any employees or not), all the employees in each department, the salary and the high end of the salary grade. If you illustrate your problem using commonly available tables, like those in the scott or hr schemas, then you don't have to post any data, just the results and the explanation. Explain how you get those results from that data. Post a little sample data (CREATE TABLE and INSERT statements) and the results you want from that data.
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