Comment

Single line: --

Multiple lines: /* */

Data Type

Key word order

  1. SELECT
  2. FROM
  3. WHERE
  4. GROUP BY
  5. HAVING
  6. ORDER BY
  7. LIMIT

SELECT

-- Query table
SELECT * FROM students
WHERE class = 5   -- <> means not equal  
ORDER BY grade, age DESC
LIMIT 5 OFFSET 5;

-- Query table
SELECT * FROM students
WHERE class = 5
ORDER BY grade, age DESC;

-- Query table
SELECT class, AVG(grade) AS avg
FROM students
GROUP BY class
HAVING grade >= 80
ORDER BY avg DESC;

-- Select few columns (rename)
SELECT name AS 'Titles', grade AS 'Score'
FROM movies;

SELECT AVG(grade) FROM students;
-- AVG, SUM, MAX, MIN, COUNT, ROUND(<>,#)

-- calculate total rows
SELECT COUNT(*) FROM students;

-- ignore NULL
SELECT COUNT(grade) FROM students;

SELECT COUNT(DISTINCT class) FROM students;

CREATE