SQL is followed by unique set of rules and guidelines called Syntax.
SQL Statements
Most of the actions you need to perform on a database are done with SQL Statments.
SQL was designed to be entered on a console and results would display back to a screen.
SELECT * FROM TableName;
Example:
SELECT * FROM Employee;
Important SQL Commands
SELECT - Read the data.
INSERT INTO - Insert or Add new data.
UPDATE - Update existing data.
DELETE - Remove or Delete data.
CREATE DATABASE - Create new database.
DROP TABLE - Deletes a table.
CREATE INDEX - Create an index.
ALTER DATABASE - Modifies or Edit database.
CREATE TABLE - Create a new table.
ALTER TABLE - Modifies or Edit table.
DROP INDEX - Remove or Delete index.
SQL Keyword are not case sensitive and some database systems required a semicolon at end of each SQL statement.
Database Tables
A database contains one or more tables.Each table is assigned with unique name.
Below is selection from the "Employee" table.
 |
| Employee Table |
The table above contains four records and four cloumns (EmployeeId, EmployeeName, Address, Salary).
