Each row in the Update Information list on the JoinDef Update & Delete Rules frame lists a table in the join and a join column in that table. If a table has more than one join column, the table name appears in more than one row.

The list in the Update column shows whether updates are permitted for the join column. The default for all join columns is No. This means that any changes to values in the join column cannot be entered into the database. Yes in the Update column allows changes to go into the database. You can allow updates to a join column in one table and yet deny them in the corresponding join column of the second table.

These update rules only apply to join columns. The other columns in a table can be updated by the user. If you want to specify that a column that is not a join column cannot be updated, you must edit the form with VIFRED.

Changing update rules can control the movement of the cursor through the fields on a form for a JoinDef. If neither table allows updates to a join column, that field becomes a display‑only field on the JoinDef form and you cannot move the cursor into it.