Technology Questions

Inheritance is the ability to create new classes based on existing classes. It is useful to reuse existing code.

UDP (User Datagram Protocol) is a communications protocol that offers a limited amount of service when messages are exchanged between computers in a network that uses the Internet Protocol (IP).

They communicate via service MVS request calls.

The foreground activity, being the most important among the other states, is only killed or terminated as a last resort, especially if it is already consuming too much memory. When a memory paging state has been reach by a foreground activity, then it is killed so that the user interface can retain its responsiveness to the user.

A database trigger is procedural code that is automatically executed in response to certain events on a particular table or view in a database. The trigger is mostly used for maintaining the integrity of the information on the database.

Syntax:

CREATE OR REPLACE TRIGGER [Trigger Name] [Before / After / Instead Of]

ON [schema].[table]

<PL/SQL subprogram>

Types of PL/SQL triggers : 

> Row trigger          - The trigger fires for each ROW affected.

> Statement trigger - The trigger is fired once when the condition is matched

> Before and After trigger - The BEFORE trigger run the trigger action before the insert, update or delete statement. The AFTER trigger runs the trigger action after the insert, update or delete statement is executes.

I/O operations like reading or writing a file is not possible with client-side javascript. However , this can be done by coding a Java applet that reads files for the script. 

One of the most common errors that you might face in join statements is 

Server: Msg 4104, Level 16, State 1, Line 1
The multi-part identifier could not be bound.

A multipart identifier is any description of a field or table that contains multiple parts - for instance MyTable.SomeRow - if it can't be bound that means there's something wrong with it - either you've got a simple typo, or a confusion between table and column. It can also be caused by using reserved words in your table or field names and not surrounding them with [].

The main reason for this error is that the source table cannot be found, for example if you have statement such as Table1.OrderDate, and then if you get error above, this means that Table1 cannot be found in the query. Sometimes you can see that source table exists in the query, but T-SQL cannot understand it, especially when you write join statements.

Instance is an object not an attribute