Guide to Oracle SQL (University at Buffalo Version)
Introduction to Databases
Wikipedia defines a database as "an organized collection of data. It is the collection of schemas, tables, queries, reports, views and other objects. The data are typically organized to model aspects of reality in a way that supports processes requiring information, such as modelling the availability of rooms in hotels in a way that supports finding a hotel with vacancies."
A schema is "its structure described in a formal language supported by the database management system (DBMS). The term "schema" refers to the organization of data as a blueprint of how the database is constructed (divided into database tables in the case of relational databases).
A table is a collection of related data held in a structured format within a database. It consists of fields (columns), and rows. In relational databases and flat file databases, a table is a set of data elements (values) using a model of vertical columns (identifiable by name) and horizontal rows (a record), the cell (field) being the unit where a row and column intersect.
Each record contains fields that hold the data for that record. A field has a data type, such as Integer (NUMBER), string (VARCHAR/LONG), date (DATE), large objects (BLOB/CLOB)).
Normalization is the process of structuring a relational database in accordance with a series of so-called normal forms in order to reduce data redundancy and improve data integrity..
SQL Developer is a graphical interface to an Oracle database. You can download SQL Developer from the Oracle download site. Installation instructions are also available on that site. You also need to download and install an Oracle database.