+ add sql exe

.env-tp

@@ -0,0 +1,2 @@
+MYSQL_ROOT_PASSWORD=password
+MYSQL_PASSWORD=password

.gitignore

@@ -1,3 +1,4 @@
 /.idea/
 **/target/
 *.iml
+*.env

.tool-versions

@@ -1,2 +1,3 @@
 java temurin-21.0.3+9.0.LTS
 maven 3.9.6
+ghc 9.8.4

README.md

@@ -1,7 +1,8 @@
 # Field Kit
 
-Meant as a collection of easy-to-use tools that cover common use cases.
+* a collection of easy-to-use tools that cover common use cases.
-WIP.
+* also serves as workspace for exercises.
+    * those results should be migrated to their respective `about-foo` once some knowledge is consolidated.
 
 ## List of Use Cases
 
@@ -20,3 +21,8 @@ WIP.
 
 * WIN
     * pyenv win
+
+
+### Haskell Kit
+
+asdf plugin add ghc

docker-compose.yaml

@@ -23,6 +23,19 @@ services:
             - ME_CONFIG_MONGODB_ADMINUSERNAME=admin
             - ME_CONFIG_MONGODB_ADMINPASSWORD=password
             - ME_CONFIG_MONGODB_SERVER=mongodb
+
+
+    mariadb:
+        image: mariadb:11.3.2-jammy
+        command: --transaction-isolation=READ-COMMITTED --log-bin=binlog --binlog-format=ROW
+        environment:
+            - MYSQL_ROOT_PASSWORD=${MYSQL_ROOT_PASSWORD}
+            - MYSQL_USER=user
+            - MYSQL_PASSWORD=${MYSQL_PASSWORD}
+            - MYSQL_DATABASE=DB
+        ports:
+            - "24001:3306"
+
 volumes:
     mongo-data:
         driver: local

exercises/sql/company.sql

@@ -0,0 +1,90 @@
+-- CREATE
+CREATE TABLE Company
+(
+    company_code VARCHAR(255) PRIMARY KEY,
+    founder      VARCHAR(255)
+);
+
+
+CREATE TABLE Lead_Manager
+(
+    lead_manager_code VARCHAR(255) PRIMARY KEY,
+    company_code      VARCHAR(255)
+);
+
+
+CREATE TABLE Senior_Manager
+(
+    senior_manager_code VARCHAR(255) PRIMARY KEY,
+    lead_manager_code   VARCHAR(255),
+    company_code        VARCHAR(255)
+);
+
+CREATE TABLE Manager
+(
+    manager_code        VARCHAR(255) PRIMARY KEY,
+    senior_manager_code VARCHAR(255),
+    lead_manager_code   VARCHAR(255),
+    company_code        VARCHAR(255)
+);
+
+CREATE TABLE Employee
+(
+    employee_code       VARCHAR(255) PRIMARY KEY,
+    manager_code        VARCHAR(255),
+    senior_manager_code VARCHAR(255),
+    lead_manager_code   VARCHAR(255),
+    company_code        VARCHAR(255)
+);
+
+-- INSERT
+
+INSERT INTO Company (company_code, founder)
+VALUES ('C001', 'Alice Johnson'),
+       ('C002', 'Bob Smith');
+
+INSERT INTO Lead_Manager (lead_manager_code, company_code)
+VALUES ('LM001', 'C001'),
+       ('LM002', 'C002');
+
+INSERT INTO Senior_Manager (senior_manager_code, lead_manager_code, company_code)
+VALUES ('SM001', 'LM001', 'C001'),
+       ('SM002', 'LM002', 'C002');
+
+INSERT INTO Manager (manager_code, senior_manager_code, lead_manager_code, company_code)
+VALUES ('M001', 'SM001', 'LM001', 'C001'),
+       ('M002', 'SM002', 'LM002', 'C002');
+
+INSERT INTO Employee (employee_code, manager_code, senior_manager_code, lead_manager_code, company_code)
+VALUES ('E001', 'M001', 'SM001', 'LM001', 'C001'),
+       ('E002', 'M001', 'SM001', 'LM001', 'C001'),
+       ('E003', 'M002', 'SM002', 'LM002', 'C002'),
+       ('E004', 'M002', 'SM002', 'LM002', 'C002');
+
+
+-- QUERY
+
+SELECT DISTINCT C.company_code,
+                C.founder,
+                COALESCE(LM.total_lead_managers, 0)   AS total_lead_managers,
+                COALESCE(SM.total_senior_managers, 0) AS total_senior_managers,
+                COALESCE(M.total_managers, 0)         AS total_managers,
+                COALESCE(E.total_employees, 0)        AS total_employees
+FROM Company AS C
+         LEFT JOIN (SELECT DISTINCT company_code,
+                                    COUNT(lead_manager_code) AS total_lead_managers
+                    FROM Lead_Manager
+                    GROUP BY company_code) AS LM ON C.company_code = LM.company_code
+         LEFT JOIN (SELECT DISTINCT company_code,
+                                    COUNT(senior_manager_code) AS total_senior_managers
+                    FROM Senior_Manager
+                    GROUP BY company_code) AS SM ON C.company_code = SM.company_code
+         LEFT JOIN (SELECT DISTINCT company_code,
+                                    COUNT(manager_code) AS total_managers
+                    FROM Manager
+                    GROUP BY company_code) AS M ON C.company_code = M.company_code
+         LEFT JOIN (SELECT DISTINCT company_code,
+                                    COUNT(employee_code) AS total_employees
+                    FROM Employee
+                    GROUP BY company_code) AS E ON C.company_code = E.company_code
+ORDER BY C.company_code;

exercises/sql/diff-counts.sql

@@ -0,0 +1,48 @@
+WITH city_counts AS (SELECT COUNT(CITY)          AS total_cities,
+                            COUNT(DISTINCT CITY) AS distinct_cities
+                     FROM STATION)
+SELECT total_cities - distinct_cities AS city_difference
+FROM city_counts;
+-- city_counts is a CTE (Common Table Expression )
+-- it is a temp table, which in this case has just one row
+
+
+--         Query the list of CITY names from STATION which have vowels (i.e., a, e, i, o, and u) as both their first and last characters.
+--             Your result cannot contain duplicates.
+SELECT DISTINCT CITY
+FROM STATION
+WHERE CITY REGEXP '^[aeiouAEIOU].*[aeiouAEIOU]$';
+
+SELECT DISTINCT CITY
+FROM STATION
+WHERE LOWER(SUBSTR(CITY, 1, 1)) IN ('a', 'e', 'i', 'o', 'u')
+  AND LOWER(SUBSTR(CITY, LENGTH(CITY), 1)) IN ('a', 'e', 'i', 'o', 'u');
+
+-- NOT start with vowels
+SELECT DISTINCT CITY
+FROM STATION
+WHERE CITY REGEXP '^[^aeiouAEIOU]'; -- ^ae.. negates the expression
+
+
+-- NOT end with vowels
+SELECT DISTINCT CITY
+FROM STATION
+WHERE CITY REGEXP '[^aeiouAEIOU]$'; -- ^ae.. negates the expression
+
+-- NOT start or END with vowels
+SELECT DISTINCT CITY
+FROM STATION
+WHERE CITY REGEXP '^[^aeiouAEIOU]'
+AND CITY REGEXP '[^aeiouAEIOU]$';
+
+
+-- order by last 3 characters, then by ID
+SELECT NAME FROM STUDENTS
+WHERE MARKS > 75
+ORDER BY SUBSTR(NAME, -3), ID;
+
+
+SELECT CITY, LENGTH(CITY) AS NAME_LENGTH
+FROM STATION
+ORDER BY LENGTH(CITY) DESC, CITY ASC
+    LIMIT 1;

exercises/sql/hackers.sql

@@ -0,0 +1,53 @@
+-- Create the HACKERS table
+CREATE TABLE HACKERS
+(
+    hacker_id INT PRIMARY KEY,
+    name      VARCHAR(255) NOT NULL
+);
+
+-- Create the SUBMISSIONS table
+CREATE TABLE SUBMISSIONS
+(
+    submission_id INT PRIMARY KEY,
+    hacker_id     INT,
+    challenge_id  INT,
+    score         INT,
+    FOREIGN KEY (hacker_id) REFERENCES HACKERS (hacker_id)
+);
+
+-- Optional: Insert some sample data into HACKERS
+INSERT INTO HACKERS (hacker_id, name)
+VALUES (1, 'Alice'),
+       (2, 'Bob'),
+       (3, 'Charlie');
+
+-- Optional: Insert some sample data into SUBMISSIONS
+INSERT INTO SUBMISSIONS (submission_id, hacker_id, challenge_id, score)
+VALUES (101, 1, 1001, 95),
+       (102, 1, 1002, 90),
+       (103, 2, 1001, 85),
+       (104, 3, 1003, 80);
+
+-- Select data to verify the setup
+SELECT *
+FROM HACKERS;
+SELECT *
+FROM SUBMISSIONS;
+
+
+SELECT H.hacker_id,
+       H.name,
+       HTS.total_score
+FROM HACKERS H
+         JOIN
+     (SELECT MaxScores.hacker_id,
+             SUM(MaxScores.max_score) AS total_score
+      FROM (SELECT S.hacker_id,
+                   MAX(S.score) AS max_score
+            FROM SUBMISSIONS S
+            GROUP BY S.hacker_id,
+                     S.challenge_id) AS MaxScores
+      GROUP BY MaxScores.hacker_id
+      HAVING SUM(MaxScores.max_score) > 0) AS HTS ON H.hacker_id = HTS.hacker_id
+ORDER BY HTS.total_score DESC,
+         H.hacker_id;

exercises/sql/population.sql

@@ -0,0 +1,39 @@
+-- CREATE
+CREATE TABLE CITY
+(
+    ID          INT PRIMARY KEY,
+    NAME        VARCHAR(255) NOT NULL,
+    COUNTRYCODE VARCHAR(3)   NOT NULL,
+    DISTRICT    VARCHAR(255) NOT NULL,
+    POPULATION  INT          NOT NULL
+);
+
+-- INSERT
+INSERT INTO CITY (ID, NAME, COUNTRYCODE, DISTRICT, POPULATION)
+VALUES (1, 'Tokyo', 'JPN', 'Tokyo', 13929286),
+       (2, 'Delhi', 'IN', 'Delhi', 16787941),
+       (3, 'Shanghai', 'CN', 'Shanghai', 24183300),
+       (4, N'São Paulo', 'BR', N'São Paulo', 12106920),
+       (5, 'Mumbai', 'IN', 'Maharashtra', 12442373),
+       (6, 'Cairo', 'EG', 'Cairo', 9500000),
+       (7, 'Dhaka', 'BD', 'Dhaka', 8906039),
+       (8, 'Mexico City', 'MX', 'Mexico City', 9209944),
+       (9, 'Beijing', 'CN', 'Beijing', 21542000),
+       (10, 'Osaka', 'JPN', 'Osaka Prefecture', 8839469);
+
+-- QUERY
+
+SELECT ROUND(AVG(POPULATION), 0) AS average_population
+FROM CITY;
+
+SELECT SUM(POPULATION)
+FROM CITY
+WHERE COUNTRYCODE = 'JPN';
+
+
+SELECT MAX(POPULATION) - MIN(POPULATION) AS population_difference
+FROM CITY;
+
+
+
+DROP TABLE CITY;

haskell-kit/hello.hs

@@ -0,0 +1,4 @@
+main =
+--    print "Hello World!"
+--    putStr "Hello World!"
+    putStrLn "Hello World!"