error during inserting data in table

You should update your data source to allow null values, or populate the data point before writing to the DS.

how aaply default here in db

you will need to populate a proper value before inserting, and if you can't do that, you'll need to modify the column in the DB table to accept null values.  There's no automatic way to make Appian insert the default value as defined in the DB, nor should there be any reason to.

The error message tells us pretty plainly (after you get used to reading through the clutter) which column this error is in reference to, BTW.

you will need to populate a proper value before inserting, and if you can't do that, you'll need to modify the column in the DB table to accept null values.  There's no automatic way to make Appian insert the default value as defined in the DB, nor should there be any reason to.

The error message tells us pretty plainly (after you get used to reading through the clutter) which column this error is in reference to, BTW.