I have an employee table in Oracle that has 100 records: some employees are managers and under these managers there...
will be some clerks, and under some clerks there will be some typists. I need to retreive the heirarchical structure of managers, ie. who is working under whom and who is the manager of whom, like manager--clerk--typist, something like a tree structure in SQL Server. Can you help me please?
Oracle has a nice?albeit non-standard?way to perform hierarchical queries: the CONNECT BY clause. Here's an example using Oracle's sample EMP table:
select lpad(' ',(Level-1)*3) || EName || ' (' || Job || ')' as "Employee Tree" from Emp connect by prior EmpNo = Mgr start with Mgr is null;And here are the resulting rows:
Employee Tree ------------------------ KING (PRESIDENT) JONES (MANAGER) SCOTT (ANALYST) ADAMS (CLERK) FORD (ANALYST) SMITH (CLERK) BLAKE (MANAGER) ALLEN (SALESMAN) WARD (SALESMAN) MARTIN (SALESMAN) TURNER (SALESMAN) JAMES (CLERK) CLARK (MANAGER) MILLER (CLERK)
For More Information
- What do you think about this answer? E-mail the edtiors at editor@searchDatabase.com with your feedback.
- The Best SQL Web Links: tips, tutorials, scripts, and more.
- Have an SQL tip to offer your fellow DBAs and developers? The best tips submitted will receive a cool prize. Submit your tip today!
- Ask your technical SQL questions -- or help out your peers by answering them -- in our live discussion forums.
- Ask the Experts yourself: Our SQL, database design, Oracle, SQL Server, DB2, metadata, object-oriented and data warehousing gurus are waiting to answer your toughest questions.
Have a question for an expert?
Please add a title for your question
Get answers from a TechTarget expert on whatever's puzzling you.