A database system typically contains multiple databases.
Each database usually contains multiple tables.
Tables store data organized in rows.
Each row contains several fields.
Each field has a number of properties, such as the field name, length, data type that will store, etc..
SQL statements are not sensitive to case-sensitive, ie 'SELECT' and 'select' are two words the same for SQL.
Some databases systems need a semicolon after each SQL statement to run properly
The semicolon can also be used to separate a SQL statement in another SQL statement on the same line.
SQL statements can be grouped by functionality:
A. - Data Definition Language (DDL).
DDL statements consists of the creation (CREATE), modification (ALTER) and clear (DROP) of the main components of a database:
2. - Data Manipulation Language (DML).
DML is composed of sentences that are used to:
3. - Data Control Language (DCL).
DCL consists of SQL statements to control the functions of management: