Using Literal Character Strings and Duplicate Rows

Using Literal Character Strings

SELECT first_name ||' is a '||job_id      AS "Employee Details"

FROM   employees;

EMPLOYEES DETAILS

John is a C_CEO

Leonardo is a F_CEO

…

Duplicate Rows

The default display of queries is all rows, including duplicate rows. By using Distinct you can eliminate repeated rows

SELECT department_id FROM   employees;

DEPARTMENT_ID

20

20

SELECT DISTINCT department_id FROM   employees;

DEPARTMENT_ID

20

10