Category Archives: Oracle

Oracle SQL/PLSQL:

INTRODUCTION

What is a Database?
  • Databases are designed to offer an organized mechanism for storing, managing and retrieving information.
  • Need for Database.
  • Different Vendors:
  • Well known DBMSs include Oracle, IBM DB2, Microsoft SQL Server, Microsoft Access, PostgreSQL, MySQL, and SQLite.
  • These companies are promoting a new, extended version of relational database technology called object-relational database management systems also known as ORDBMSs.
DBMS Vs. RDBMS
  • Relationship among tables is maintained in a RDBMS whereas this not the case DBMS as it is used to manage the database.
  • DBMS accepts the ‘flat file’ data that means there is no relation among different data whereas RDBMS does not accepts this type of design.
  • DBMS is used for simpler business applications whereas RDBMS is used for more complex applications.
  • Although the foreign key concept is supported by both DBMS and RDBMS but its only RDBMS that enforces the rules.
  • RDBMS solution is required by large sets of data whereas small sets of data can be managed by DBMS.

SQL (Structured Query Language):

SQL is a fourth generation language.

SQL is divided into the following:

  1. Data Definition Language (DDL)
  2. Data Manipulation Language (DML)
  3. Data Retrieval Language (DRL)
  4. Transaction Control Language (TCL)
  5. Data Control Language (DCL)

DDL — create, alter, drop, truncate, rename

DML — insert, update, deleteDRL — select
TCL — commit, rollback, savepoint
DCL — grant, revoke

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