Object-Relational Mapper

• FIXME

Terms defined: active record, Build manager

FIXME: create object-relational mapper

Issue 45

• SQL requires parts of query in an odd order
• So create active records using the Builder pattern
• Does not scale up to more complex queries
  • Have to build an expression tree in memory and rearrange clauses for that
• Thanks to Mike Bayer for advice
• select_all.py: get all rows of table using reflection to get table name
• get_metadata.py: cache table description and convert row tuples to dictionaries
• simpler_metadata.py: let SQLite do that
• choose_columns.py: select columns using immediate string formatting
  • test get-all case as well as getting specific columns
  • exercise: re-introduce cached metadata to do error handling
• delay_columns.py: have query save the column names for later use in run method
  • complicates things now, but becomes useful later
• aggregate.py: add aggregation
  • columns can now be string or aggregates
  • exercise: add group-by
• insert.py: insert values
  • go back to keeping metadata in class (which may add startup overheads for large programs)
  • exercise: handle insertion of multiple records
  • exercise: handle insertion of objects with appropriately-named fields