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Specifying an identity column
194 DataWindow .NET
Specifying an identity column
Many DBMSs allow you to specify that the value for a column in a new row is
to be automatically assigned by the DBMS. This kind of column is called an
identity column. Different DBMSs provide different types of identity columns.
For example, some DBMSs allow you to define autoincrement columns so that
the column for a new row is automatically assigned a value one greater than
that of the previous highest value. You could use this feature to specify that an
order number be automatically incremented when someone adds a new order:
By specifying an identity column in the Specify Update Properties dialog box,
you tell DataWindow Designer to bring back the value of a new row's identity
column after an insert in the DataWindow object so that users can see it.
For information about identity columns in your DBMS, see your DBMS
documentation.
Specifying updatable columns
You can make all or some of the columns in a table updatable.
Updatable columns are displayed highlighted. Click a nonupdatable column to
make it updatable. Click an updatable column to make it nonupdatable.
Changing tab values
If you have changed the updatability of a column, you should change its tab
value. If you have allowed a column to be updated, you should change its tab
value to a nonzero number so users can tab to it.