Technology Questions

A unique constraint on a column uniquely identifies the record by a combination of one or more fields. Few unique constraint fields can have a NULL value as long as the combination of values is unique.

Example:
create table employee ( id number NOT NULL, dob DATE, professor_id NOT NULL, Name varchar(200) Constraint id_unique UNIQUE(id,dob) );

A delegate declares a ref type that references a named of anonymous method. Delegates are secure and type-safe. Consider them as type safe function pointers.

The server version of a Windows operating system is designed to provide more optimized networking services over a network. It can manage domains better and it includes more security feature and data backup support. Workstation versions act merely as clients and therefore do not need to have as much resources when compared to the server versions.

Even though both PL/SQL and Java (or) .NET can be used, PL/SQL stands above these two in terms of integration overhead. This is because Java is an open source proprietary and Data manipulation is slightly faster in PL/SQL than in Java. 

Oracle NOT NULL is used on a column to ensure that the value for that column can never be NULL.
Example:
Below, the constraint is that the id should never be NULL. If it is, oracle throws an error.
create table employee ( id number NOT NULL, Name varchar(200) );

ClassName refName = new ClassName();

or

ClassName refName;

refName = new ClassName();

Anonymous class is class without name.

EX:

class A {

}

class Demo {

    A r = new A() {

        }; //anonymous class

}

Number, String, Boolean, Function, Object, Null, Undefined.