There are tables: "Units of measurement" code name
"Substances" code code_unit_measurement name
"Substances" substance code code number
I use QSqlTableModel and QTableView to display the "Substance Inputs" table. It is necessary that in the table in addition to the fields of the table “Substances of substances” the unit of measurement is displayed (one more column). Should it be done via LEFT JOIN? That is, inherit from QSqlTableModel and make your own query?