is a set of data written in a strictly defined manner in corresponding structures
assumed data model. In the present case data and computer are included
A program that specializes in the collection and processing of these data. The database
is composed of different elements. The most important of them is a record split into several
The fields in which the information for each category is stored. For example, in
Address Book Each record is a collection of information about one person. It consists of
Several fields that hold such information as name, address, telephone number, etc.
Each field contains data for a separate category.
Relational Database Management System (RDBMS, literally a management system
relational database) is a set of programs used to use a database
based on the relational model.
Structural query language used to create, modify databases and to
Placing and retrieving data from databases. SQL is a declarative language.
The decision to store and download data is left to the system
Database management (DBMS). The use of SQL, according to its name, consists in
querying the database. Queries can be counted as one of three
• SQL DML (Data Manipulation Language)
• SQL DDL (“Data Definition Language”),
• SQL DCL (Data Control Language).
DML (Data Manipulation Language) is used to perform data operations – to them
inserting, deleting, viewing, changing. The most important command of this
The set is:
• SELECT – retrieve data from the database,
• INSERT – data entry in the database,
• UPDATE – change data,
• DELETE – delete data from the database.
With DDL (Data Definition Language) you can operate on data structures
are stored – ie, add, change and delete tables or databases.
The most important commands of this group are:
• CREATE (eg CREATE TABLE, CREATE DATABASE, …) – create a structure
(database, table, index, etc.)
• DROP (eg DROP TABLE, DROP DATABASE, …) – removal of structure,
• ALTER (eg ALTER TABLE ADD COLUMN …) – change the structure (add a column
to the table, change the data type in the table column).
The DCL (Data Control Language) is used to grant object permissions
database. The most important commands in this group are:
• GRANT (eg GRANT ALL PRIVILEGES ON EMPLOYEES TO PIOTR WITH GRANT
OPTION) – grant all rights to the EMPLOYEES table to the PIOTR user
An option allows you to assign rights to this table.
• REVOKE – the user has been given all rights to the table that were given
granted by the GRANT command.