Lesson 01

Retrieving Data Using the SQL SELECT Statement

Basic SELECT Statement

Select *| {[DISTINCT] column|expression [alias],....}
From table;

Select identifies the columns to be displayed.
From identifies the table containing those columns.

Select *
From departments;

Writing SQL Statements

# SQL statements are not case-sensitive.
# SQL statements can be entered on one or more lines.
# Keywords cannot be abbreviated or split acros lines.
# Clauses are usually placed on separete lines.
# Indents are used to enhance readability.
# In SQL Developer, SQL statements can optionally be terminated by a semicolon(;).
# Semicolons are required when you execute multiple SQL statements.
# In SQL*Plus, you are required to end each SQL statement with a semicolon(;)

select department_id
from departments;

select last_name, salary, salary + 300
from employees;

select last_name, salary, 12*salary+100
from employees;

select last_name, salary, 12*(salary+100)
from employees;

select last_name, job_id, salary, commission_pct
from employees;

select last_name, 12*salary*commission_pct
from employees;

select last_name AS name, commission_pct com
from employees;

select last_name "name", salary*12 "annual salary"
from employees;

select last_name||job_id as "employees"
from employees;

select last_name || ' is a '|| job_id as "employee details"
from employees;

select department_name || q'[ Department's Manager ID:]' || manager_id as "department and manager"
from departments;

select department_id
from employees;

select distinct department_id
from employees;

describe employees;

SELECT first_name, last_name, job_id, salary AS yearly
FROM   employees;