Keep it true · 10
The database changes
A model that is connected checks itself against the live database and shows what moved: a column renamed, a table dropped. That is the difference between a model that checks itself and documentation somebody has to remember to update.
- Someone opens a connected model, or asks for a check. The check runs for a model that has a database behind it.
- The model is held against the database as it is today. Every table, every column and every column a join relies on.
- The live tables and columns are read. Only their names and shapes, never the rows.
- Each part is found to be there, missing, or possibly renamed. Where something is missing and the database has a likely replacement, that candidate is named as a possibility, not applied.
- What moved is shown on the model. Marked on the drawing where it sits, counted in a line across the top, and listed so each one can be jumped to and checked again.
Which databases. SQL Server today, and the other engines are next. Until then a model on one of them says it was not checked, and nothing is flagged.