Schema Design

Derive Row Values in SQLite with Generated Columns

Applications often store values that can be calculated from other columns: an order-line total from quantity and unit price, a normalized search key from text, or a duration from two timestamps. The tempting approach is to calculate the value in application code and save both the inputs and the result. That creates two sources of truth. If one code path updates the inputs but forgets to update the derived value, the row becomes internally inconsistent.