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.
It returns the left-hand operand if the operand is not null; otherwise it returns the right hand operand.Remarks. A nullable type can represent a value from the typeâs domain, or the value can be undefined (in which case the value is null).You can use the ?? operatorâs syntactic expressiveness to return an appropriate value (the right hand operand) when the left operand has a nullible type whose value is null.If you try to assign a nullable value type to a non-nullable value type without using the ?? operator, you will generate a compile-time error.ou can use the ?? operatorâs syntactic expressiveness to return an appropriate value (the right hand operand) when the left operand has a nullible type whose value is null. If you try to assign a nullable value type to a non-nullable value type without using the ?? operator, you will generate a compile-time error.