Further status definitions are possible for maintenance views:

• read and change: Existing view entries can be changed. Records cannot be deleted or inserted.
• read and change (time-dependent views) : Only entries can be inserted whose non-time-dependent part of the key (see Time-Dependent Key Parts) is identical to that of existing entries.

Only read access is permitted for database views that are defined over several tables. You therefore have to select the maintenance status read only for such views.

If a database view is created for a single transparent table, data can be inserted in this table with the view. The behavior when inserting a data record for a table field not contained in the view depends on whether NULL values are permitted for this field:

• If the field is defined in the database as NOT NULL with initial value, the field is filled with the corresponding initial value.
• If the field is defined in the database as NOT NULL without initial value, an insert is not possible. This results in a database error.
• If the field is not defined in the database as NOT NULL, there will be a NULL value in this field.

For this reason you should not maintain any records in a table with database views if an initial value is not defined for the field, i.e. the field is not defined as NOT NULL with initial values (see Initial Values).

Changing records that are already in the table with a database view is not critical if the database view contains all the key fields of the table.

When you insert data records with maintenance views or projection views, all the table fields not contained in the view are assigned the default value of the field. This does not depend on whether the field is defined in the database as NOT NULL. This avoids NULL values in these fields.