(Without diminishing Keith's suggestions:) The plethora of solution approaches is more due to the power of specifying set relationships via queries than SQLite's virtue alone. SQLite, among other DBMS's, accepts SQL for specifying the result sets of query operations, and compiles it to create a program targeting its own dedicated virtual machine which is specialized for querying and modifying the connected or attached DB(s). The flexibility you see arises from the flexibility of (and some redundancy in) SQL, combined with skilled use of it.