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How does one code a hierarchical tree-structured query?

April 26, 2017code Hierarchical query tree-structured

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How does one code a hierarchical tree-structured query?

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10 Posted

The SCOTT/TIGER database schema contains a table EMP with a self-referencing relation (EMPNO and MGR columns). This table is perfect for testing and demonstrating tree-structured queries as the MGR column contains the employee number of the “current” employee’s boss. The LEVEL pseudo-column is an indication of how deep in the tree one is. Oracle can handle queries with a depth of up to 255 levels.