Foreign keys

DBTrarzan is a database browser that uses foreign keys to traverse the tables of a relational database. Foreign keys are used in the database as constraints, but they contain information about the relationships among tables. DBTarzan sees a foreign key as a directed relation between 2 tables, composed by:

• a owner table (the table containing the foreign key, also called child)
• a referenced table (the table referenced by the foreign key, also called parent)
• the owner columns, the columns in the owner table that are part of the foreign key
• the referenced columns, the columns in the referenced table that are part of the foreign key

DBTarzan uses the foreign key to traverse the database:

• from the owner table to the referenced table
• also in the opposite direction, from the referenced table to the owner table.

This happens in the following way:

• The user selects (checks) one or more rows in a table (we call it from table)
• The user activates the foreign key to a table that we call the to table
• For each selected row, DBTarzan:
  • reads the values of the foreign key columns in the from table,
  • in the to table it finds all the rows that match with their foreign keys columns values the from table values.
  • it shows these rows in the result.