Null example sentences

This is achieved by using NULL in Where clause while specifying the condition.Null value implies that we cannot identify such tuples or identify these as alike.A special value called Null is used to represent unknown or not applicable values of attributes in a tuple.Its value cannot be null and therefore its Allow Zero Length property must be set to No with Required property being Yes.The value of Type cannot be null because of total participation of Accounts in classify relationship.Accordingly, its value cannot be null and therefore its Allow Zero Length property must be set to No with Required property being Yes.It is also possible to devise different types of code values for different types of null value situation.In other words, a null value is also acceptable to the database.Its Required property is set to No with Allow Zero Length property being Yes to imply that null values are also permitted.This is because the overall boss of the organisation, although an employee, does not have any boss and therefore a null value in this field is to be allowed to accommodate the situation.Its value cannot be null and therefore its Allow Zero Length property must be set to No with Required Property being Yes.For a single field primary key, Access sets the Required property to Yes and the Indexed property to Yes (No duplicates) because a primary key by definition must have unique values without null entries.The values of PrepBy and AuthBy cannot be null because of total participation of vouchers in PrepBy and Authby relationships.The values of debit and credit cannot be null because of total participation of vouchers in debit and credit relationship.States that no primary key value can be null because it is used to identify individual tuple in a relation.