The Field Overrides option in File Specifications allows you to specify certain field characteristics for fields in external databases (such as Oracle, Sybase, ODBC, etc.). Once you have chosen this option and selected the desired field, the Field Overrides Detail overlay appears as shown in Figure 3-10 below.
Figure 3-10. Field Overrides Detail Overlay
The following field overrides can be designated:
· Column Name explicitly designates the column name that will be used in the external database for this field. If left blank, APPX will construct the column name from the field name.
· Column Type explicitly designates the data type for this column in the external database. If left blank, APPX will default the data type based on the APPX data dictionary specifications for this field.
· Null OK? indicates whether or not the value of this field can be left blank. Click the checkbox to toggle between “yes” 
and “no” 
.