A view is nothing but a window of an existing table by which one can view and can also change the values in tables. The main point aspect of view is views have no storage space. For this reason views are also called as virtual tables. Thus in other words a view is a database object that gives a logical representation of one or more database tables. As...

The Evolution of Database systems File Management System Hierarchical database System  Network Database System  Relational Database System File Management System The file management system also called as FMS in short is one in which all data is stored on a single large file. The main disadvantage in this system...

COUNT is a group function returns  result by summarizing multiple rows. All group by value function will have the usage of DISTINCT or ALL option and so is the COUNT which uses the DISTINCT option. DISTINCT option is used to enforce uniqueness and  if combined with COUNT is used to count only unique mentioned value. To understand this let...

Stored procedures are compiled collection of programs or SQL statements that live in the database. A stored procedure can access and modify data present in many tables. Also a stored procedure is not associated with any particular database object. But triggers are event-driven special procedures which are attached to a specific database object say...

The main important aspect is physical data model is created after logical data model. For designing a logical data model one need not have through knowledge in any specific RDBMS like oracle Informix and so on. This is because logical data model is created after having through study of the business entities which would be involved in the application....

E.codd designed 12 rules that stated rules for database to be relational. 1. The Information Rule For a database to be relational all information is represented as data values in tables. 2. The Rule of Guaranteed Access The data represented in table by using table name column name and primary key value defined for that table. 3. The systematic treatment...

Oracle Net Services provides enterprise-wide connectivity solutions in distributed heterogeneous computing environments. Oracle Net Services eases the complexities of network configuration and management maximizes performance and improves network diagnostic capabilities. Oracle Net a component of Oracle Net Services enables a network session from...

Truncate command will delete all records and the most important thing to make note of truncate command is since truncate command cannot be rolled back one must make sure to take proper backup of table data before performing the truncate command. Truncate command is thus used to remove all rows from either a table or a cluster. If one wants to use the...

DECODE is used to decode a CHAR or VARCHAR2 or NUMBER into any of several different character strings or numbers based on value. That is DECODE does a value-by-value substitution. For every value that is given in the DECODE function it makes an if then check and matches the value. The general format of DECODE function is given below DECODE value if1 then1 if2 then2 else In...

You can also use tnsping utility on command prompt to check Oracle Net connectivity. Follow these steps to check the connection to particular SID. Open Command prompt. Write tnsping SID for the database connectivity you want to check If you get the message Used TNSNAMES adapter to resolve the alias” then tnsping utility is...