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:
- Data Definition Language (DDL)
- Data Manipulation Language (DML)
- Data Retrieval Language (DRL)
- Transaction Control Language (TCL)
- Data Control Language (DCL)
DDL — create, alter, drop, truncate, rename
DML — insert, update, deleteDRL — select
TCL — commit, rollback, savepoint
DCL — grant, revoke