Specifies null permissions for a field: NULLS ALLOWED, NOT NULL, or NOT NULL WITH DEFAULT. If a table exists then this command is ignored. The syntax is:
NULL_PERM = {Y | N | D} [, {Y | N | D}] ...;
where the specification is listed in the same order as the corresponding field names, and delimited by commas.
If NULL_PERM is Y then null values are permitted in the column. If NULL_PERM is N, then the column is prevented from containing null values. If NULL_PERM is D, then null values are converted to a specified default value for the column (NOT NULL WITH DEFAULT). The default value is dependent on the data type.
For example:
NULL_PERM = n,n,n,y,y,d,d;