In addition to the the Commonwealth Ensign, there are three other official Australian ensigns: 1  The Australian Red Ensign - Merchant Navy, as for the Australian flag, but with a red field with white stars. 2  The Australian White Ensign - Royal Australian Navy - as for the Australian flag but with a white field and dark blue stars.
Null (or NULL) is a special marker used in Structured Query Language to indicate that a data value does not exist in the database. Introduced by the creator of the relational database model, E. F. Codd, SQL Null serves to fulfil the requirement that all true relational database management systems (RDBMS) support a representation of missing information and inapplicable information.
While NULL really means not set, in the context of this question I believe the above statement is correct. There are a number of reasons for a column to have a NULL value: 1  The column is not appropriate to the sub-type or state of the row.2  The value is not available, or hasn't been recorded in the column.hile NULL really means not set, in the context of this question I believe the above statement is correct. There are a number of reasons for a column to have a NULL value: 1  The column is not appropriate to the sub-type or state of the row.