In this post, we’re going to discuss a very useful SQL extension to work with hierarchal queries. This is sadly only implemented by Oracle and although a few other databases support it as well, it won’t work in PostgreSQL, MySql nor SQL Server. The dataset Let’s create a very simple hierarchal dataset to work with. CREATE TABLE GeoArea ( parentName VARCHAR2(100), code VARCHAR2(100) ); INSERT INTO GeoArea VALUES (NULL, 'World'); INSERT INTO GeoArea VALUES ('World', 'Europe'); INSERT INTO...
