5.schema Objects

Schema Objects

Schema

-          Collection of Logical structures of data or schema Objects

-          Owned by database user and has same name as user name. Schema objects are created & manipulated by sql.  Ex.MANA0809.

-          Schema Objects (logical data storage structure): Tables,Indexes,Views…

   

 Tables:

   -  Basic unit of data storage structure. Data stored in rows & columns

   -  To define a table structure by create table  employ_master (id number(10),         Employ_name(25), Join_dt date).

  -  Row identifies an  instance entity ,Column identifies Attributes of entity.

•          Specify a rules on each column by using integrity constraints.(Null,Not null,Unique…)

Indexes:

•          Optional Structures associated with tables. We can create indexes one or more column to Speed up the execution.

•           Create Index  Emp_idx on Emply_master(employ_No);

•          If we drop on index means that not affect table.

Data Access  Languages

   -To Access data from database using language Sql,Plsql

 SQL:

•          Query data 

•          Insert, update, and delete rows in a table

•          Create, replace, alter, and drop objects

•          Control access to the database and its objects

•          Guarantee database consistency and integrity

Oracle SQL is an implementation of the ANSI standard

Ø  PL/SQL

•          Extension of  Oracle Sql

•           Performs  to Store ,Retrieve, Manipulate data from database.

•          Functions,Procedures,Pakages that contains set of sql operations to solve specific  task

•          To store Application Logic in database