clase 2

SELECT SUBSTR(first_name||' '||last_name,1,3) AS Nombre
FROM employees;

SELECT first_name, last_name
FROM employees;

SELECT first_name||' '||last_name AS Nombre
FROM employees
WHERE last_name LIKE '%s';

describe employees;

SELECT
  first_name||' '||last_name AS Nombre,
  DEPARTMENT_ID

FROM employees
ORDER BY DEPARTMENT_ID;

SELECT
    DEPARTMENT_ID
    , COUNT(*)
    , SUM(salary)
    , MAX (salary)
    , MIN (salary)
    , AVG (salary)
FROM employees
GROUP BY DEPARTMENT_ID
ORDER BY DEPARTMENT_ID
;