How to Run MySQL Using Docker

How to Run MySQL and phpMyAdmin Using Docker

• SQL
• MySQL
• Docker Setup
• MySQL Keywords
• MySQL Databases
• MySQL Tables
  • SELECT with AND
  • SELECT multiple fields
  • SELECT with DISTINCT and MOD
  • Count duplicates
  • Find the shortest and longest strings ordered alphabetically
  • Find unique strings that starts with vowels
  • Find unique strings that ends with vowels
  • Find unique strings that starts or ends with vowels
  • Find unique strings that does not starts with vowels
  • Find unique strings that does not ends with vowels
  • Find unique strings that does not starts or ends with vowels
  • Find unique strings that does not starts and ends with vowels
  • LEFT and RIGHT
  • Ascending order
  • GROUP BY, GROUP_CONCAT, FLOOR, AVG with JOIN
  • IF with JOIN
  • BETWEEN with JOIN
  • Joining tables
    • INNER JOIN
    • OUTER JOIN
      • LEFT JOIN
      • RIGHT JOIN
      • FULL OUTER JOIN
  • CASE
  • COUNT(*)
  • ROUND
  • MIN and MAX
  • REPLACE
  • LIMIT
  • Find duplicates
  • IN
  • Like
  • Output query results to a file
• Miscellaneous
• Resources

SQL

SQL, "sequel"; Structured Query Language) is a domain-specific language used in programming and designed for managing data held in a relational database management system (RDBMS), or for stream processing in a relational data stream management system (RDSMS). It is particularly useful in handling structured data, i.e. data incorporating relations among entities and variables.

MySQL

MySQL is an open-source relational database management system (RDBMS).

Docker Setup

Run the following command from the same directory, where the docker-compose.yml file is located.

docker-compose up

access the running container mysql-snippets_db_1

docker exec -it mysql-snippets_db_1 bash

MySQL Keywords

Keywords

Data types

No	Name	Example	Doc
1	Numeric		link
2	Date and Time		link
3	String		link
5	Spatial		link
6	JSON		link

MySQL Databases

Run the MySQl queries from this file students.sql from the MySQL CLI.

mysql -uroot -proot

or import the sql file.

mysql -uroot -p test_db < school.sql

Type the password root and you're done.

SHOW DATABASES;
USE test_db;

SELECT * FROM students;

Create a new database.

CREATE DATABASE test_db_1;

Delete a database. This will delete all the tables within the database.

DROP DATABASE test_db_1;

MySQL Tables

Show all tables in a database.

SHOW TABLES;

+-------------------+
| Tables_in_test_db |
+-------------------+
| marks             |
| students          |
+-------------------+
2 rows in set (0.00 sec)

Delete a table. If you don't have a storage issue, it's best practise that you rename the table and after few weeks later when you are sure that there are no issues, then you can delete the table.

DROP TABLE table_name;

Rename a table. Be aware that one or more application can be using the old table name

RENAME TABLE old_table_name TO new_table_name;

Copy a table.

CREATE TABLE new_table_name TO old_table_name;
INSERT new_table_name SELECT * FROM old_table_name;

SELECT with AND

SELECT * FROM students WHERE first_name='Bob' and postcode=23031;

+----+------------+----------------+----------------+------------------+--------+-----------------------+---------------------------------------------------------+----------+---------------+
| id | first_name | last_name      | city           | phone            | gender | email                 | address                                                 | postcode | date_of_birth |
+----+------------+----------------+----------------+------------------+--------+-----------------------+---------------------------------------------------------+----------+---------------+
|  5 | Bob        | Schulistland   | Schulistland   | 895-877-0076x197 | Male   | scbob@opensource.org  | 39405 Nicolas Walk Apt. 041 Kozeychester, AL 20566-8063 |    23031 | 2019-07-15    |
| 16 | Bob        | Port Thoraland | Port Thoraland | 1-628-108-7615   | Male   | pobob@ycombinator.com | 9256 Price Summit Garrickland, KY 23867                 |    23031 | 2016-02-05    |
+----+------------+----------------+----------------+------------------+--------+-----------------------+---------------------------------------------------------+----------+---------------+
2 rows in set (0.00 sec)

SELECT multiple fields

SELECT city, postcode FROM students;

+---------------------+----------+
| city                | postcode |
+---------------------+----------+
| Rathmouth           |    23031 |
| Port Lolamouth      |    27108 |
| Lavernastad         |    76631 |
| Ethelville          |    37965 |
| Schulistland        |    23031 |
| Kennithside         |    23031 |
| Oberbrunnerchester  |    24772 |
| Marcoport           |       16 |
| New Adalineton      |    89650 |
| East Kayla          |    45934 |
| Kevinmouth          |     7820 |
| North Deondreland   |    32292 |
| Port Adrianaborough |    55848 |
| South Hunter        |    29257 |
| East Breanne        |    49701 |
| Port Thoraland      |    23031 |
| West Jedediahville  |    80323 |
| Franeckiland        |    39741 |
| Lake Clare          |    24982 |
| Beattyburgh         |     7864 |
| Oberbrunnerport     |    36356 |
| Ricofort            |    69978 |
| East Graycefurt     |    49614 |
| West Joeport        |    16353 |
| Oceanestad          |    70534 |
| Creolashire         |    58634 |
| North Ernestinaton  |    90902 |
| Jakaylaland         |    10160 |
| North Esta          |    40221 |
| West Breanabury     |    23031 |
+---------------------+----------+
30 rows in set (0.00 sec)

SELECT with DISTINCT and MOD

SELECT DISTINCT first_name FROM students WHERE MOD(postcode, 2) = 0;

+------------+
| first_name |
+------------+
| Hounson    |
| Blewmen    |
| Vanacci    |
| Marflitt   |
| Pietesch   |
| Henrique   |
| Tynan      |
| Pinkard    |
| Whale      |
| Ori        |
| Tagg       |
| Costerd    |
| Corrin     |
| Lumley     |
| Whiles     |
| Presdee    |
| Bedberry   |
+------------+
17 rows in set (0.00 sec)

Count duplicates

SELECT (COUNT(postcode)-COUNT(DISTINCT(postcode))) FROM students;

+---------------------------------------------+
| (COUNT(postcode)-COUNT(DISTINCT(postcode))) |
+---------------------------------------------+
|                                           4 |
+---------------------------------------------+
1 row in set (0.00 sec)

Find the shortest and longest strings ordered alphabetically

SELECT first_name, LENGTH(first_name) FROM students ORDER BY LENGTH(first_name) DESC, first_name ASC LIMIT 1;

+-------------+--------------------+
| first_name  | LENGTH(first_name) |
+-------------+--------------------+
| Whaplington |                 11 |
+-------------+--------------------+
1 row in set (0.00 sec)

SELECT first_name, LENGTH(first_name) FROM students ORDER BY LENGTH(first_name) ASC, first_name ASC LIMIT 1;

+------------+--------------------+
| first_name | LENGTH(first_name) |
+------------+--------------------+
| Bob        |                  3 |
+------------+--------------------+
1 row in set (0.00 sec)

Find unique strings that starts with vowels

SELECT DISTINCT first_name FROM students WHERE first_name REGEXP '^[aeiou]';

+------------+
| first_name |
+------------+
| Ailn       |
| Ori        |
+------------+
2 rows in set (0.01 sec)

Find unique strings that ends with vowels

SELECT DISTINCT first_name FROM students WHERE first_name REGEXP '[aeiou]$';

+------------+
| first_name |
+------------+
| Vanacci    |
| Henrique   |
| Leeke      |
| Whale      |
| Ori        |
| Presdee    |
+------------+
6 rows in set (0.00 sec)

Find unique strings that starts or ends with vowels

SELECT DISTINCT first_name FROM students WHERE first_name REGEXP '^[aeiou].*[aeiou]$';

+------------+
| first_name |
+------------+
| Ori        |
+------------+
1 row in set (0.00 sec)

Find unique strings that does not starts with vowels

SELECT DISTINCT first_name FROM students WHERE first_name NOT REGEXP '^[aeiou]';

+-------------+
| first_name  |
+-------------+
| Hounson     |
| Tison       |
| Surmeyers   |
| Bob         |
| Holdey      |
| Blewmen     |
| Vanacci     |
| Marflitt    |
| Pietesch    |
| Henrique    |
| Tynan       |
| Pinkard     |
| Haslock     |
| Rickell     |
| Boxhill     |
| Leeke       |
| Whale       |
| Tagg        |
| Costerd     |
| Corrin      |
| Bunford     |
| Lumley      |
| Whiles      |
| Presdee     |
| Bedberry    |
| Danilchev   |
| Whaplington |
+-------------+
27 rows in set (0.00 sec)

Find unique strings that does not ends with vowels

SELECT DISTINCT first_name FROM students WHERE first_name NOT REGEXP '[aeiou]$';

+-------------+
| first_name  |
+-------------+
| Ailn        |
| Hounson     |
| Tison       |
| Surmeyers   |
| Bob         |
| Holdey      |
| Blewmen     |
| Marflitt    |
| Pietesch    |
| Tynan       |
| Pinkard     |
| Haslock     |
| Rickell     |
| Boxhill     |
| Tagg        |
| Costerd     |
| Corrin      |
| Bunford     |
| Lumley      |
| Whiles      |
| Bedberry    |
| Danilchev   |
| Whaplington |
+-------------+
23 rows in set (0.01 sec)

Find unique strings that does not starts or ends with vowels

SELECT DISTINCT first_name FROM students WHERE first_name NOT REGEXP '^[aeiou].*[aeiou]$';

+-------------+
| first_name  |
+-------------+
| Ailn        |
| Hounson     |
| Tison       |
| Surmeyers   |
| Bob         |
| Holdey      |
| Blewmen     |
| Vanacci     |
| Marflitt    |
| Pietesch    |
| Henrique    |
| Tynan       |
| Pinkard     |
| Haslock     |
| Rickell     |
| Boxhill     |
| Leeke       |
| Whale       |
| Tagg        |
| Costerd     |
| Corrin      |
| Bunford     |
| Lumley      |
| Whiles      |
| Presdee     |
| Bedberry    |
| Danilchev   |
| Whaplington |
+-------------+
28 rows in set (0.00 sec)

Find unique strings that does not starts and ends with vowels

SELECT DISTINCT first_name FROM students WHERE first_name NOT REGEXP '^[aeiou]' AND first_name NOT REGEXP '[aeiou]$';

+-------------+
| first_name  |
+-------------+
| Hounson     |
| Tison       |
| Surmeyers   |
| Bob         |
| Holdey      |
| Blewmen     |
| Marflitt    |
| Pietesch    |
| Tynan       |
| Pinkard     |
| Haslock     |
| Rickell     |
| Boxhill     |
| Tagg        |
| Costerd     |
| Corrin      |
| Bunford     |
| Lumley      |
| Whiles      |
| Bedberry    |
| Danilchev   |
| Whaplington |
+-------------+
22 rows in set (0.00 sec)

LEFT and RIGHT

SELECT first_name, LEFT(first_name, 3), RIGHT(first_name, 3) FROM  students;

+-------------+---------------------+----------------------+
| first_name  | LEFT(first_name, 3) | RIGHT(first_name, 3) |
+-------------+---------------------+----------------------+
| Ailn        | Ail                 | iln                  |
| Hounson     | Hou                 | son                  |
| Tison       | Tis                 | son                  |
| Surmeyers   | Sur                 | ers                  |
| Bob         | Bob                 | Bob                  |
| Holdey      | Hol                 | dey                  |
| Blewmen     | Ble                 | men                  |
| Vanacci     | Van                 | cci                  |
| Marflitt    | Mar                 | itt                  |
| Pietesch    | Pie                 | sch                  |
| Henrique    | Hen                 | que                  |
| Tynan       | Tyn                 | nan                  |
| Pinkard     | Pin                 | ard                  |
| Haslock     | Has                 | ock                  |
| Rickell     | Ric                 | ell                  |
| Bob         | Bob                 | Bob                  |
| Boxhill     | Box                 | ill                  |
| Leeke       | Lee                 | eke                  |
| Whale       | Wha                 | ale                  |
| Ori         | Ori                 | Ori                  |
| Tagg        | Tag                 | agg                  |
| Costerd     | Cos                 | erd                  |
| Corrin      | Cor                 | rin                  |
| Bunford     | Bun                 | ord                  |
| Lumley      | Lum                 | ley                  |
| Whiles      | Whi                 | les                  |
| Presdee     | Pre                 | dee                  |
| Bedberry    | Bed                 | rry                  |
| Danilchev   | Dan                 | hev                  |
| Whaplington | Wha                 | ton                  |
+-------------+---------------------+----------------------+
30 rows in set (0.00 sec)

Ascending order

SELECT first_name from students ORDER BY first_name ASC;

+-------------+
| first_name  |
+-------------+
| Ailn        |
| Bedberry    |
| Blewmen     |
| Bob         |
| Bob         |
| Boxhill     |
| Bunford     |
| Corrin      |
| Costerd     |
| Danilchev   |
| Haslock     |
| Henrique    |
| Holdey      |
| Hounson     |
| Leeke       |
| Lumley      |
| Marflitt    |
| Ori         |
| Pietesch    |
| Pinkard     |
| Presdee     |
| Rickell     |
| Surmeyers   |
| Tagg        |
| Tison       |
| Tynan       |
| Vanacci     |
| Whale       |
| Whaplington |
| Whiles      |
+-------------+
30 rows in set (0.00 sec)

GROUP BY, GROUP_CONCAT, FLOOR, AVG with JOIN

SELECT students.id, students.first_name, students.last_name, FLOOR(AVG(marks.mark)), GROUP_CONCAT(marks.subject) FROM students JOIN marks
ON students.id = marks.student_id
GROUP BY students.id;

+----+------------+--------------------+------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| id | first_name | last_name          | FLOOR(AVG(marks.mark)) | GROUP_CONCAT(marks.subject)                                                                                                                                      |
+----+------------+--------------------+------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|  1 | Ailn       | Rathmouth          |                     85 | Alien Ethics,Foreign Arts,Space Travel,Alien Dance History,Planetary Ecology                                                                                     |
|  2 | Hounson    | Port Lolamouth     |                     52 | Mathematics,Planetary History                                                                                                                                    |
|  3 | Tison      | Lavernastad        |                     63 | Magic Survival,Foreign Ethics,Foreign Statistics,Foreign Pathology,Galactic History                                                                              |
|  4 | Surmeyers  | Ethelville         |                     71 | Necromancy,Dimensional Manipulation,Nutrition Recognition,Transmutation,Planetary Geography,Alien Economics,Magic Music,Magic Rituals,Foreign Instrumental Music |
|  5 | Bob        | Schulistland       |                     76 | Alien Medicine                                                                                                                                                   |
|  6 | Holdey     | Kennithside        |                     57 | Alien Physiology,Alien Social Studies,Magic Music,Intergallactic Relations,Herbalism,Foreign Arts                                                                |
|  7 | Blewmen    | Oberbrunnerchester |                     75 | Foreign Political Sciences,Military Law,Alien Bioengineering,Foreign Social Skills,Foreign History                                                               |
|  8 | Vanacci    | Marcoport          |                     64 | Foreign Services,Alien Social Skills,Alien Genealogy,Terraforming                                                                                                |
|  9 | Marflitt   | New Adalineton     |                     48 | Grand Strategy,Magic Arts,Foreign Evolutionary Biology                                                                                                           |
+----+------------+--------------------+------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------+
9 rows in set (0.00 sec)

IF with JOIN

SELECT students.id, IF(marks.mark < 50, "Fail", "Pass"), marks.subject AS result FROM students JOIN marks
ON students.id = marks.student_id;

+----+-------------------------------------+------------------------------+
| id | IF(marks.mark < 50, "Fail", "Pass") | result                       |
+----+-------------------------------------+------------------------------+
|  3 | Fail                                | Magic Survival               |
|  4 | Pass                                | Planetary Geography          |
|  9 | Pass                                | Foreign Evolutionary Biology |
|  6 | Pass                                | Intergallactic Relations     |
|  9 | Fail                                | Grand Strategy               |
|  7 | Pass                                | Foreign History              |
|  1 | Pass                                | Alien Dance History          |
|  7 | Pass                                | Foreign Social Skills        |
|  8 | Pass                                | Alien Social Skills          |
|  4 | Pass                                | Magic Music                  |
|  8 | Pass                                | Alien Genealogy              |
|  4 | Pass                                | Magic Rituals                |
|  1 | Pass                                | Planetary Ecology            |
|  7 | Pass                                | Military Law                 |
|  3 | Pass                                | Foreign Ethics               |
|  4 | Pass                                | Foreign Instrumental Music   |
|  8 | Pass                                | Foreign Services             |
|  4 | Pass                                | Alien Economics              |
|  1 | Pass                                | Alien Ethics                 |
|  9 | Fail                                | Magic Arts                   |
|  6 | Fail                                | Alien Social Studies         |
|  7 | Pass                                | Foreign Political Sciences   |
|  8 | Pass                                | Terraforming                 |
|  4 | Pass                                | Transmutation                |
|  1 | Pass                                | Space Travel                 |
|  5 | Pass                                | Alien Medicine               |
|  3 | Pass                                | Foreign Statistics           |
|  4 | Pass                                | Necromancy                   |
|  6 | Fail                                | Magic Music                  |
|  2 | Fail                                | Planetary History            |
|  6 | Pass                                | Herbalism                    |
|  4 | Fail                                | Dimensional Manipulation     |
|  4 | Pass                                | Nutrition Recognition        |
|  3 | Pass                                | Foreign Pathology            |
|  6 | Pass                                | Foreign Arts                 |
|  7 | Pass                                | Alien Bioengineering         |
|  6 | Pass                                | Alien Physiology             |
|  2 | Pass                                | Mathematics                  |
|  1 | Pass                                | Foreign Arts                 |
|  3 | Pass                                | Galactic History             |
+----+-------------------------------------+------------------------------+
40 rows in set (0.01 sec)

BETWEEN with JOIN

SELECT students.id, marks.mark, marks.subject FROM students JOIN marks
ON students.id = marks.student_id
WHERE marks.mark BETWEEN 90 AND 100;

+----+------+---------------------+
| id | mark | subject             |
+----+------+---------------------+
|  1 | 98   | Alien Dance History |
|  4 | 91   | Alien Economics     |
|  1 | 91   | Alien Ethics        |
|  1 | 98   | Space Travel        |
|  3 | 98   | Foreign Statistics  |
|  4 | 100  | Necromancy          |
+----+------+---------------------+
6 rows in set (0.00 sec)

Joining tables

INNER JOIN

In MySQL, JOIN, CROSS JOIN, and INNER JOIN are syntactic equivalents (they can replace each other).

An inner join will give you all common rows in both A and B.

SELECT s.first_name, s.last_name, m.mark
FROM students AS s JOIN marks AS m
ON m.student_id = s.id
ORDER BY m.mark;

+------------+--------------------+------+
| first_name | last_name          | mark |
+------------+--------------------+------+
| Holdey     | Kennithside        |    0 |
| Tison      | Lavernastad        |   23 |
| Marflitt   | New Adalineton     |   23 |
| Surmeyers  | Ethelville         |   34 |
| Hounson    | Port Lolamouth     |   34 |
| Holdey     | Kennithside        |   34 |
| Marflitt   | New Adalineton     |   45 |
| Blewmen    | Oberbrunnerchester |   54 |
| Surmeyers  | Ethelville         |   56 |
| Tison      | Lavernastad        |   56 |
| Vanacci    | Marcoport          |   56 |
| Surmeyers  | Ethelville         |   56 |
| Tison      | Lavernastad        |   57 |
| Holdey     | Kennithside        |   58 |
| Vanacci    | Marcoport          |   59 |
| Vanacci    | Marcoport          |   65 |
| Surmeyers  | Ethelville         |   67 |
| Ailn       | Rathmouth          |   69 |
| Hounson    | Port Lolamouth     |   71 |
| Ailn       | Rathmouth          |   72 |
| Blewmen    | Oberbrunnerchester |   76 |
| Vanacci    | Marcoport          |   76 |
| Surmeyers  | Ethelville         |   76 |
| Surmeyers  | Ethelville         |   76 |
| Bob        | Schulistland       |   76 |
| Marflitt   | New Adalineton     |   77 |
| Blewmen    | Oberbrunnerchester |   79 |
| Blewmen    | Oberbrunnerchester |   80 |
| Holdey     | Kennithside        |   81 |
| Holdey     | Kennithside        |   83 |
| Tison      | Lavernastad        |   84 |
| Blewmen    | Oberbrunnerchester |   87 |
| Holdey     | Kennithside        |   88 |
| Surmeyers  | Ethelville         |   89 |
| Ailn       | Rathmouth          |   91 |
| Surmeyers  | Ethelville         |   91 |
| Ailn       | Rathmouth          |   98 |
| Tison      | Lavernastad        |   98 |
| Ailn       | Rathmouth          |   98 |
| Surmeyers  | Ethelville         |  100 |
+------------+--------------------+------+
40 rows in set (0.00 sec)

OUTER JOIN

LEFT JOIN

A left outer join will give all rows in A, plus any common rows in B.

SELECT s.first_name, s.last_name, m.mark FROM students AS s
    LEFT JOIN marks AS m ON m.student_id = s.id
ORDER BY m.mark;

+-------------+---------------------+------+
| first_name  | last_name           | mark |
+-------------+---------------------+------+
| Whaplington | West Breanabury     | NULL |
| Boxhill     | West Jedediahville  | NULL |
| Bob         | Port Thoraland      | NULL |
| Rickell     | East Breanne        | NULL |
| Haslock     | South Hunter        | NULL |
| Pinkard     | Port Adrianaborough | NULL |
| Tynan       | North Deondreland   | NULL |
| Henrique    | Kevinmouth          | NULL |
| Pietesch    | East Kayla          | NULL |
| Leeke       | Franeckiland        | NULL |
| Whale       | Lake Clare          | NULL |
| Ori         | Beattyburgh         | NULL |
| Tagg        | Oberbrunnerport     | NULL |
| Costerd     | Ricofort            | NULL |
| Corrin      | East Graycefurt     | NULL |
| Bunford     | West Joeport        | NULL |
| Presdee     | North Ernestinaton  | NULL |
| Lumley      | Oceanestad          | NULL |
| Danilchev   | North Esta          | NULL |
| Bedberry    | Jakaylaland         | NULL |
| Whiles      | Creolashire         | NULL |
| Holdey      | Kennithside         |    0 |
| Marflitt    | New Adalineton      |   23 |
| Tison       | Lavernastad         |   23 |
| Hounson     | Port Lolamouth      |   34 |
| Surmeyers   | Ethelville          |   34 |
| Holdey      | Kennithside         |   34 |
| Marflitt    | New Adalineton      |   45 |
| Blewmen     | Oberbrunnerchester  |   54 |
| Vanacci     | Marcoport           |   56 |
| Surmeyers   | Ethelville          |   56 |
| Tison       | Lavernastad         |   56 |
| Surmeyers   | Ethelville          |   56 |
| Tison       | Lavernastad         |   57 |
| Holdey      | Kennithside         |   58 |
| Vanacci     | Marcoport           |   59 |
| Vanacci     | Marcoport           |   65 |
| Surmeyers   | Ethelville          |   67 |
| Ailn        | Rathmouth           |   69 |
| Hounson     | Port Lolamouth      |   71 |
| Ailn        | Rathmouth           |   72 |
| Blewmen     | Oberbrunnerchester  |   76 |
| Vanacci     | Marcoport           |   76 |
| Surmeyers   | Ethelville          |   76 |
| Bob         | Schulistland        |   76 |
| Surmeyers   | Ethelville          |   76 |
| Marflitt    | New Adalineton      |   77 |
| Blewmen     | Oberbrunnerchester  |   79 |
| Blewmen     | Oberbrunnerchester  |   80 |
| Holdey      | Kennithside         |   81 |
| Holdey      | Kennithside         |   83 |
| Tison       | Lavernastad         |   84 |
| Blewmen     | Oberbrunnerchester  |   87 |
| Holdey      | Kennithside         |   88 |
| Surmeyers   | Ethelville          |   89 |
| Surmeyers   | Ethelville          |   91 |
| Ailn        | Rathmouth           |   91 |
| Tison       | Lavernastad         |   98 |
| Ailn        | Rathmouth           |   98 |
| Ailn        | Rathmouth           |   98 |
| Surmeyers   | Ethelville          |  100 |
+-------------+---------------------+------+
61 rows in set (0.00 sec)

RIGHT JOIN

A right outer join will give all rows in B, plus any common rows in A.

SELECT s.first_name, s.last_name, m.mark FROM students AS s
    RIGHT JOIN marks AS m ON m.student_id = s.id
ORDER BY m.mark;

+------------+--------------------+------+
| first_name | last_name          | mark |
+------------+--------------------+------+
| Holdey     | Kennithside        |    0 |
| Tison      | Lavernastad        |   23 |
| Marflitt   | New Adalineton     |   23 |
| Surmeyers  | Ethelville         |   34 |
| Hounson    | Port Lolamouth     |   34 |
| Holdey     | Kennithside        |   34 |
| Marflitt   | New Adalineton     |   45 |
| Blewmen    | Oberbrunnerchester |   54 |
| Surmeyers  | Ethelville         |   56 |
| Tison      | Lavernastad        |   56 |
| Vanacci    | Marcoport          |   56 |
| Surmeyers  | Ethelville         |   56 |
| Tison      | Lavernastad        |   57 |
| Holdey     | Kennithside        |   58 |
| Vanacci    | Marcoport          |   59 |
| Vanacci    | Marcoport          |   65 |
| Surmeyers  | Ethelville         |   67 |
| Ailn       | Rathmouth          |   69 |
| Hounson    | Port Lolamouth     |   71 |
| Ailn       | Rathmouth          |   72 |
| Blewmen    | Oberbrunnerchester |   76 |
| Vanacci    | Marcoport          |   76 |
| Surmeyers  | Ethelville         |   76 |
| Surmeyers  | Ethelville         |   76 |
| Bob        | Schulistland       |   76 |
| Marflitt   | New Adalineton     |   77 |
| Blewmen    | Oberbrunnerchester |   79 |
| Blewmen    | Oberbrunnerchester |   80 |
| Holdey     | Kennithside        |   81 |
| Holdey     | Kennithside        |   83 |
| Tison      | Lavernastad        |   84 |
| NULL       | NULL               |   84 |
| Blewmen    | Oberbrunnerchester |   87 |
| Holdey     | Kennithside        |   88 |
| Surmeyers  | Ethelville         |   89 |
| Ailn       | Rathmouth          |   91 |
| Surmeyers  | Ethelville         |   91 |
| Ailn       | Rathmouth          |   98 |
| Tison      | Lavernastad        |   98 |
| Ailn       | Rathmouth          |   98 |
| Surmeyers  | Ethelville         |  100 |
+------------+--------------------+------+
41 rows in set (0.00 sec)

FULL OUTER JOIN

A full outer join will give you all the rows in A and all the rows in B. We can use the follwing code to emulate full outer joins.

SELECT s.first_name, s.last_name, m.mark FROM students AS s
   LEFT JOIN marks AS m ON m.student_id = s.id
UNION ALL
SELECT s.first_name, s.last_name, m.mark FROM students AS s
   RIGHT JOIN marks AS m ON m.student_id = s.id
WHERE s.id is null;

+-------------+---------------------+------+
| first_name  | last_name           | mark |
+-------------+---------------------+------+
| Ailn        | Rathmouth           |   72 |
| Ailn        | Rathmouth           |   98 |
| Ailn        | Rathmouth           |   91 |
| Ailn        | Rathmouth           |   69 |
| Ailn        | Rathmouth           |   98 |
| Hounson     | Port Lolamouth      |   71 |
| Hounson     | Port Lolamouth      |   34 |
| Tison       | Lavernastad         |   84 |
| Tison       | Lavernastad         |   56 |
| Tison       | Lavernastad         |   98 |
| Tison       | Lavernastad         |   57 |
| Tison       | Lavernastad         |   23 |
| Surmeyers   | Ethelville          |   67 |
| Surmeyers   | Ethelville          |   34 |
| Surmeyers   | Ethelville          |  100 |
| Surmeyers   | Ethelville          |   76 |
| Surmeyers   | Ethelville          |   91 |
| Surmeyers   | Ethelville          |   56 |
| Surmeyers   | Ethelville          |   89 |
| Surmeyers   | Ethelville          |   76 |
| Surmeyers   | Ethelville          |   56 |
| Bob         | Schulistland        |   76 |
| Holdey      | Kennithside         |   81 |
| Holdey      | Kennithside         |   88 |
| Holdey      | Kennithside         |   58 |
| Holdey      | Kennithside         |    0 |
| Holdey      | Kennithside         |   34 |
| Holdey      | Kennithside         |   83 |
| Blewmen     | Oberbrunnerchester  |   80 |
| Blewmen     | Oberbrunnerchester  |   54 |
| Blewmen     | Oberbrunnerchester  |   79 |
| Blewmen     | Oberbrunnerchester  |   87 |
| Blewmen     | Oberbrunnerchester  |   76 |
| Vanacci     | Marcoport           |   56 |
| Vanacci     | Marcoport           |   59 |
| Vanacci     | Marcoport           |   76 |
| Vanacci     | Marcoport           |   65 |
| Marflitt    | New Adalineton      |   23 |
| Marflitt    | New Adalineton      |   45 |
| Marflitt    | New Adalineton      |   77 |
| Pietesch    | East Kayla          | NULL |
| Henrique    | Kevinmouth          | NULL |
| Tynan       | North Deondreland   | NULL |
| Pinkard     | Port Adrianaborough | NULL |
| Haslock     | South Hunter        | NULL |
| Rickell     | East Breanne        | NULL |
| Bob         | Port Thoraland      | NULL |
| Boxhill     | West Jedediahville  | NULL |
| Leeke       | Franeckiland        | NULL |
| Whale       | Lake Clare          | NULL |
| Ori         | Beattyburgh         | NULL |
| Tagg        | Oberbrunnerport     | NULL |
| Costerd     | Ricofort            | NULL |
| Corrin      | East Graycefurt     | NULL |
| Bunford     | West Joeport        | NULL |
| Lumley      | Oceanestad          | NULL |
| Whiles      | Creolashire         | NULL |
| Presdee     | North Ernestinaton  | NULL |
| Bedberry    | Jakaylaland         | NULL |
| Danilchev   | North Esta          | NULL |
| Whaplington | West Breanabury     | NULL |
| NULL        | NULL                |   84 |
+-------------+---------------------+------+
62 rows in set (0.00 sec)

CASE

SELECT
    CASE
        WHEN marks.mark >= 90 AND marks.mark <= 100 THEN "A"
        WHEN marks.mark >= 80 AND marks.mark <= 89 THEN "B"
        WHEN marks.mark >= 70 AND marks.mark <= 79 THEN "C"
        WHEN marks.mark >= 60 AND marks.mark <= 69 THEN "D"
        WHEN marks.mark >= 50 AND marks.mark <= 59 THEN "E"
        ELSE "F"
    END AS grades
FROM marks
ORDER BY grades;

+--------+
| grades |
+--------+
| A      |
| A      |
| A      |
| A      |
| A      |
| A      |
| B      |
| B      |
| B      |
| B      |
| B      |
| B      |
| B      |
| B      |
| C      |
| C      |
| C      |
| C      |
| C      |
| C      |
| C      |
| C      |
| C      |
| D      |
| D      |
| D      |
| E      |
| E      |
| E      |
| E      |
| E      |
| E      |
| E      |
| E      |
| F      |
| F      |
| F      |
| F      |
| F      |
| F      |
| F      |
+--------+
41 rows in set (0.00 sec)

SELECT marks.mark,
    CASE
        WHEN marks.mark >= 90 AND marks.mark <= 100 THEN "A"
        WHEN marks.mark >= 80 AND marks.mark <= 89 THEN "B"
        WHEN marks.mark >= 70 AND marks.mark <= 79 THEN "C"
        WHEN marks.mark >= 60 AND marks.mark <= 69 THEN "D"
        WHEN marks.mark >= 50 AND marks.mark <= 59 THEN "E"
        ELSE "F"
    END AS grades
FROM marks
ORDER BY grades;

+------+--------+
| mark | grades |
+------+--------+
|  100 | A      |
|   91 | A      |
|   91 | A      |
|   98 | A      |
|   98 | A      |
|   98 | A      |
|   84 | B      |
|   81 | B      |
|   80 | B      |
|   88 | B      |
|   89 | B      |
|   87 | B      |
|   84 | B      |
|   83 | B      |
|   76 | C      |
|   76 | C      |
|   72 | C      |
|   71 | C      |
|   79 | C      |
|   76 | C      |
|   76 | C      |
|   76 | C      |
|   77 | C      |
|   69 | D      |
|   67 | D      |
|   65 | D      |
|   56 | E      |
|   56 | E      |
|   58 | E      |
|   56 | E      |
|   54 | E      |
|   59 | E      |
|   56 | E      |
|   57 | E      |
|   34 | F      |
|    0 | F      |
|   34 | F      |
|   34 | F      |
|   23 | F      |
|   45 | F      |
|   23 | F      |
+------+--------+
41 rows in set (0.00 sec)

SELECT students.id, marks.mark, marks.subject,
    CASE
        WHEN marks.mark >= 90 AND marks.mark <= 100 THEN "A"
        WHEN marks.mark >= 80 AND marks.mark <= 89 THEN "B"
        WHEN marks.mark >= 70 AND marks.mark <= 79 THEN "C"
        WHEN marks.mark >= 60 AND marks.mark <= 69 THEN "D"
        WHEN marks.mark >= 50 AND marks.mark <= 59 THEN "E"
        ELSE "F"
     END AS grades
FROM students
    JOIN marks ON students.id = marks.student_id
ORDER BY grades;

+----+------+------------------------------+--------+
| id | mark | subject                      | grades |
+----+------+------------------------------+--------+
|  4 |  100 | Necromancy                   | A      |
|  4 |   91 | Alien Economics              | A      |
|  1 |   91 | Alien Ethics                 | A      |
|  3 |   98 | Foreign Statistics           | A      |
|  1 |   98 | Alien Dance History          | A      |
|  1 |   98 | Space Travel                 | A      |
|  6 |   81 | Alien Physiology             | B      |
|  7 |   80 | Alien Bioengineering         | B      |
|  6 |   88 | Foreign Arts                 | B      |
|  4 |   89 | Magic Rituals                | B      |
|  7 |   87 | Foreign Social Skills        | B      |
|  3 |   84 | Galactic History             | B      |
|  6 |   83 | Intergallactic Relations     | B      |
|  4 |   76 | Transmutation                | C      |
|  5 |   76 | Alien Medicine               | C      |
|  1 |   72 | Foreign Arts                 | C      |
|  2 |   71 | Mathematics                  | C      |
|  7 |   79 | Military Law                 | C      |
|  8 |   76 | Alien Genealogy              | C      |
|  4 |   76 | Magic Music                  | C      |
|  7 |   76 | Foreign History              | C      |
|  9 |   77 | Foreign Evolutionary Biology | C      |
|  1 |   69 | Planetary Ecology            | D      |
|  4 |   67 | Nutrition Recognition        | D      |
|  8 |   65 | Alien Social Skills          | D      |
|  4 |   56 | Planetary Geography          | E      |
|  3 |   56 | Foreign Pathology            | E      |
|  6 |   58 | Herbalism                    | E      |
|  8 |   56 | Terraforming                 | E      |
|  7 |   54 | Foreign Political Sciences   | E      |
|  8 |   59 | Foreign Services             | E      |
|  4 |   56 | Foreign Instrumental Music   | E      |
|  3 |   57 | Foreign Ethics               | E      |
|  2 |   34 | Planetary History            | F      |
|  6 |    0 | Magic Music                  | F      |
|  4 |   34 | Dimensional Manipulation     | F      |
|  6 |   34 | Alien Social Studies         | F      |
|  9 |   23 | Magic Arts                   | F      |
|  9 |   45 | Grand Strategy               | F      |
|  3 |   23 | Magic Survival               | F      |
+----+------+------------------------------+--------+
40 rows in set (0.00 sec)

COUNT(*)

The COUNT(*) function returns the number of rows in a result set returned by a SELECT statement. It returns the number of rows including duplicate, non-NULL and NULL rows.

SELECT
    CASE
        WHEN marks.mark >= 90 AND marks.mark <= 100 THEN "A"
        WHEN marks.mark >= 80 AND marks.mark <= 89 THEN "B"
        WHEN marks.mark >= 70 AND marks.mark <= 79 THEN "C"
        WHEN marks.mark >= 60 AND marks.mark <= 69 THEN "D"
        WHEN marks.mark >= 50 AND marks.mark <= 59 THEN "E"
        ELSE "F"
     END AS grades,
COUNT(*) AS count
FROM students
    JOIN marks ON students.id = marks.student_id
GROUP BY grades
ORDER BY grades;

+--------+-------+
| grades | count |
+--------+-------+
| A      |     6 |
| B      |     7 |
| C      |     9 |
| D      |     3 |
| E      |     8 |
| F      |     7 |
+--------+-------+
6 rows in set (0.00 sec)

ROUND

SELECT ROUND(SUM(mark), 2) FROM marks;

+---------------------+
| ROUND(SUM(mark), 2) |
+---------------------+
|             2777.00 |
+---------------------+
1 row in set (0.00 sec)

MIN and MAX

SELECT MAX(mark), MIN(mark) FROM marks;

+-----------+-----------+
| MAX(mark) | MIN(mark) |
+-----------+-----------+
|       100 |         0 |
+-----------+-----------+
1 row in set (0.00 sec)

REPLACE

SELECT subject, REPLACE(subject, 'Magic', 'Sorcery') FROM marks;

+------------------------------+--------------------------------------+
| subject                      | REPLACE(subject, 'Magic', 'Sorcery') |
+------------------------------+--------------------------------------+
| Magic Survival               | Sorcery Survival                     |
| Planetary Geography          | Planetary Geography                  |
| Foreign Evolutionary Biology | Foreign Evolutionary Biology         |
| Intergallactic Relations     | Intergallactic Relations             |
| Grand Strategy               | Grand Strategy                       |
| Foreign History              | Foreign History                      |
| Alien Dance History          | Alien Dance History                  |
| Foreign Social Skills        | Foreign Social Skills                |
| Alien Social Skills          | Alien Social Skills                  |
| Magic Music                  | Sorcery Music                        |
| Alien Genealogy              | Alien Genealogy                      |
| Magic Rituals                | Sorcery Rituals                      |
| Planetary Ecology            | Planetary Ecology                    |
| Military Law                 | Military Law                         |
| Foreign Ethics               | Foreign Ethics                       |
| Foreign Instrumental Music   | Foreign Instrumental Music           |
| Foreign Services             | Foreign Services                     |
| Alien Economics              | Alien Economics                      |
| Alien Ethics                 | Alien Ethics                         |
| Magic Arts                   | Sorcery Arts                         |
| Alien Social Studies         | Alien Social Studies                 |
| Foreign Political Sciences   | Foreign Political Sciences           |
| Terraforming                 | Terraforming                         |
| Transmutation                | Transmutation                        |
| Space Travel                 | Space Travel                         |
| Alien Medicine               | Alien Medicine                       |
| Foreign Statistics           | Foreign Statistics                   |
| Necromancy                   | Necromancy                           |
| Magic Music                  | Sorcery Music                        |
| Planetary History            | Planetary History                    |
| Herbalism                    | Herbalism                            |
| Dimensional Manipulation     | Dimensional Manipulation             |
| Nutrition Recognition        | Nutrition Recognition                |
| Foreign Pathology            | Foreign Pathology                    |
| Foreign Arts                 | Foreign Arts                         |
| Alien Bioengineering         | Alien Bioengineering                 |
| Alien Physiology             | Alien Physiology                     |
| Mathematics                  | Mathematics                          |
| Foreign Arts                 | Foreign Arts                         |
| Galactic History             | Galactic History                     |
| Galactic History             | Galactic History                     |
+------------------------------+--------------------------------------+
41 rows in set (0.00 sec)

LIMIT

SELECT * FROM marks
LIMIT 1;

+----+------------+------+----------------+
| id | student_id | mark | subject        |
+----+------------+------+----------------+
|  1 |          3 |   23 | Magic Survival |
+----+------------+------+----------------+
1 row in set (0.00 sec)

LIMIT x, y means return y rows, starting from xth row.

SELECT * FROM marks
LIMIT 0, 5;

+----+------------+------+------------------------------+
| id | student_id | mark | subject                      |
+----+------------+------+------------------------------+
|  1 |          3 |   23 | Magic Survival               |
|  2 |          4 |   56 | Planetary Geography          |
|  3 |          9 |   77 | Foreign Evolutionary Biology |
|  4 |          6 |   83 | Intergallactic Relations     |
|  5 |          9 |   45 | Grand Strategy               |
+----+------------+------+------------------------------+
5 rows in set (0.01 sec)

Find duplicates

SELECT subject, count(*) FROM marks
GROUP BY subject
HAVING count(*) > 1;

+------------------+----------+
| subject          | count(*) |
+------------------+----------+
| Magic Music      |        2 |
| Foreign Arts     |        2 |
| Galactic History |        2 |
+------------------+----------+
3 rows in set (0.00 sec)

IN

SELECT * FROM marks
WHERE subject IN ('Magic Music');

+----+------------+------+-------------+
| id | student_id | mark | subject     |
+----+------------+------+-------------+
| 10 |          4 |   76 | Magic Music |
| 29 |          6 |    0 | Magic Music |
+----+------------+------+-------------+
2 rows in set (0.01 sec)

Like

• % - any sequence of zero, one, or multiple characters
• _ - matches a single character

To match % or _ use a backslash as a prefix.

SHOW DATABASES LIKE 'test%';

+------------------+
| Database (test%) |
+------------------+
| test_db          |
+------------------+
1 row in set (0.00 sec)

SHOW DATABASES LIKE 'test\_d_';

+---------------------+
| Database (test\_d_) |
+---------------------+
| test_db             |
+---------------------+
1 row in set (0.00 sec)

Output query results to a file

Miscellaneous

SELECT REPEAT('* ', 1);
SELECT REPEAT('* ', 2);
SELECT REPEAT('* ', 3);
SELECT REPEAT('* ', 4);
SELECT REPEAT('* ', 5);
SELECT REPEAT('* ', 6);
SELECT REPEAT('* ', 7);
SELECT REPEAT('* ', 8);
SELECT REPEAT('* ', 9);
SELECT REPEAT('* ', 10);
SELECT REPEAT('* ', 11);
SELECT REPEAT('* ', 12);
SELECT REPEAT('* ', 13);
SELECT REPEAT('* ', 14);
SELECT REPEAT('* ', 15);
SELECT REPEAT('* ', 16);
SELECT REPEAT('* ', 17);
SELECT REPEAT('* ', 18);
SELECT REPEAT('* ', 19);
SELECT REPEAT('* ', 20);

SELECT elt(locate(operation, "+-*/"), a+b, a-b, a*b, a/b) = c

Resources

1. SQL
2. MySQL
3. filldb
4. mockaroo
5. fantasynamegenerators
6. join
7. what-is-the-difference-between-inner-join-and-outer-join
8. how-to-write-full-outer-join-in-mysql
9. MySQL Tutorial for Beginners
10. COUNT(*)
11. sql
12. Planetscale courses
13. File Space Management