Solution: Jose Torres

employees.sql

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+--  Sample employee database 
+--  See changelog table for details
+--  Copyright (C) 2007,2008, MySQL AB
+--  
+--  Original data created by Fusheng Wang and Carlo Zaniolo
+--  http://www.cs.aau.dk/TimeCenter/software.htm
+--  http://www.cs.aau.dk/TimeCenter/Data/employeeTemporalDataSet.zip
+-- 
+--  Current schema by Giuseppe Maxia 
+--  Data conversion from XML to relational by Patrick Crews
+-- 
+-- This work is licensed under the 
+-- Creative Commons Attribution-Share Alike 3.0 Unported License. 
+-- To view a copy of this license, visit 
+-- http://creativecommons.org/licenses/by-sa/3.0/ or send a letter to 
+-- Creative Commons, 171 Second Street, Suite 300, San Francisco, 
+-- California, 94105, USA.
+-- 
+--  DISCLAIMER
+--  To the best of our knowledge, this data is fabricated, and
+--  it does not correspond to real people. 
+--  Any similarity to existing people is purely coincidental.
+-- 
+
+DROP DATABASE IF EXISTS employees;
+CREATE DATABASE IF NOT EXISTS employees;
+USE employees;
+
+SELECT 'CREATING DATABASE STRUCTURE' as 'INFO';
+
+DROP TABLE IF EXISTS dept_emp,
+                     dept_manager,
+                     titles,
+                     salaries, 
+                     employees, 
+                     departments;
+
+/*!50503 set default_storage_engine = InnoDB */;
+/*!50503 select CONCAT('storage engine: ', @@default_storage_engine) as INFO */;
+
+CREATE TABLE employees (
+    emp_no      INT             NOT NULL,
+    birth_date  DATE            NOT NULL,
+    first_name  VARCHAR(14)     NOT NULL,
+    last_name   VARCHAR(16)     NOT NULL,
+    gender      ENUM ('M','F')  NOT NULL,    
+    hire_date   DATE            NOT NULL,
+    PRIMARY KEY (emp_no)
+);
+
+CREATE TABLE departments (
+    dept_no     CHAR(4)         NOT NULL,
+    dept_name   VARCHAR(40)     NOT NULL,
+    PRIMARY KEY (dept_no),
+    UNIQUE  KEY (dept_name)
+);
+
+CREATE TABLE dept_manager (
+   emp_no       INT             NOT NULL,
+   dept_no      CHAR(4)         NOT NULL,
+   from_date    DATE            NOT NULL,
+   to_date      DATE            NOT NULL,
+   FOREIGN KEY (emp_no)  REFERENCES employees (emp_no)    ON DELETE CASCADE,
+   FOREIGN KEY (dept_no) REFERENCES departments (dept_no) ON DELETE CASCADE,
+   PRIMARY KEY (emp_no,dept_no)
+); 
+
+CREATE TABLE dept_emp (
+    emp_no      INT             NOT NULL,
+    dept_no     CHAR(4)         NOT NULL,
+    from_date   DATE            NOT NULL,
+    to_date     DATE            NOT NULL,
+    FOREIGN KEY (emp_no)  REFERENCES employees   (emp_no)  ON DELETE CASCADE,
+    FOREIGN KEY (dept_no) REFERENCES departments (dept_no) ON DELETE CASCADE,
+    PRIMARY KEY (emp_no,dept_no)
+);
+
+CREATE TABLE titles (
+    emp_no      INT             NOT NULL,
+    title       VARCHAR(50)     NOT NULL,
+    from_date   DATE            NOT NULL,
+    to_date     DATE,
+    FOREIGN KEY (emp_no) REFERENCES employees (emp_no) ON DELETE CASCADE,
+    PRIMARY KEY (emp_no,title, from_date)
+) 
+; 
+
+CREATE TABLE salaries (
+    emp_no      INT             NOT NULL,
+    salary      INT             NOT NULL,
+    from_date   DATE            NOT NULL,
+    to_date     DATE            NOT NULL,
+    FOREIGN KEY (emp_no) REFERENCES employees (emp_no) ON DELETE CASCADE,
+    PRIMARY KEY (emp_no, from_date)
+) 
+; 
+
+CREATE OR REPLACE VIEW dept_emp_latest_date AS
+    SELECT emp_no, MAX(from_date) AS from_date, MAX(to_date) AS to_date
+    FROM dept_emp
+    GROUP BY emp_no;
+
+# shows only the current department for each employee
+CREATE OR REPLACE VIEW current_dept_emp AS
+    SELECT l.emp_no, dept_no, l.from_date, l.to_date
+    FROM dept_emp d
+        INNER JOIN dept_emp_latest_date l
+        ON d.emp_no=l.emp_no AND d.from_date=l.from_date AND l.to_date = d.to_date;

query.sql

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+-- *** INSERT ***
+
+-- insert 15 employees
+INSERT INTO `employees` (`emp_no`, `birth_date`, `first_name`, `last_name`, `gender`, `hire_date`)
+VALUES (1, '1988-10-15', 'Jose', 'Torres', 'F', '2022-01-01'),
+       (2, '1978-10-15', 'Dayan', 'Alvarez', 'M', '2022-02-01'),
+       (3, '1990-10-15', 'Isaura', 'Marti', 'F', '2022-03-01'),
+       (4, '1934-10-15', 'Alvaro', 'Sanchez', 'M', '2022-04-01'),
+       (5, '1955-10-15', 'Sergi', 'Clemente', 'M', '2022-05-01'),
+       (6, '1988-10-15', 'Miquel', 'Abella', 'M', '2022-06-01'),
+       (7, '1987-10-15', 'Luis', 'Alarcon', 'M', '2022-07-01'),
+       (8, '1943-10-15', 'David', 'Pizarro', 'M', '2022-08-01'),
+       (9, '1922-10-15', 'Lucia', 'del Cacho', 'F', '2022-09-01'),
+       (10, '2000-10-15', 'Berta', 'Garcia', 'F', '2022-10-01'),
+       (11, '1999-10-15', 'Victor', 'Jauregui', 'M', '2022-11-01'),
+       (12, '1973-10-15', 'David', 'Moina', 'M', '2022-12-01'),
+       (13, '1925-10-15', 'Antonio', 'Rufino', 'M', '2023-01-01'),
+       (14, '1996-10-15', 'Javier', 'TorPascual', 'M', '2023-02-01'),
+       (15, '1987-10-15', 'Jesus', 'Velazquez', 'M', '2023-03-01');
+
+-- 5 employees must have at least two salaries in different ranges of dates and different amounts
+INSERT INTO `salaries` (`emp_no`, `salary`, `from_date`, `to_date`) 
+VALUES (1, 35000, '2022-01-01', '2022-06-01'),
+       (1, 40000, '2022-07-01', '2022-12-01'),
+       (2, 45000, '2022-02-01', '2022-07-01'),
+       (2, 50000, '2022-08-01', '2022-12-01'),
+       (3, 45000, '2022-03-01', '2022-08-01'),
+       (3, 50000, '2022-09-01', '2022-12-01'),
+       (4, 40000, '2022-04-01', '2022-09-01'),
+       (4, 45000, '2022-10-01', '2022-12-01'),
+       (5, 35000, '2022-05-01', '2022-10-01'),
+       (5, 40000, '2022-11-01', '2022-12-01');
+
+-- insert departament
+INSERT INTO `departments` (`dept_no`, `dept_name`) 
+VALUES ('d1', 'Developer'), 
+       ('d2', 'Manager'), 
+       ('d3', 'Analyst'), 
+       ('d4', 'Consultant'), 
+       ('d5', 'Director'), 
+       ('d6', 'Architect'), 
+       ('d7', 'Engineer'), 
+       ('d8', 'Designer'), 
+       ('d9', 'Programmer'), 
+       ('d10', 'Coordinator');
+
+-- 10 employees belong to more than one department
+INSERT INTO `dept_emp` (`emp_no`, `dept_no`, `from_date`, `to_date`) 
+VALUES ('1', 'd1', '2023-01-20', '2033-01-20'), 
+       ('1', 'd7', '2023-01-20', '2033-01-20'), 
+       ('2', 'd3', '2022-01-05', '2032-01-05'), 
+       ('2', 'd4', '2022-01-05', '2032-01-05'), 
+       ('3', 'd4', '2020-01-20', '2030-01-20'), 
+       ('3', 'd3', '2020-01-20', '230-01-20'), 
+       ('4', 'd5', '2000-10-20', '2010-10-20'), 
+       ('4', 'd3', '2000-10-20', '2010-10-20'), 
+       ('5', 'd6', '2003-04-20', '2013-04-20'), 
+       ('5', 'd8', '2003-04-20', '2013-04-20'), 
+       ('6', 'd9', '2075-01-20', '2085-01-20'), 
+       ('6', 'd10', '2075-01-20', '2085-01-20'), 
+       ('7', 'd1', '2040-06-20', '2050-06-20'), 
+       ('7', 'd7', '2040-06-20', '2030-06-20'), 
+       ('8', 'd6', '2086-01-20', '2096-01-20'), 
+       ('8', 'd8', '2086-01-20', '2096-01-20'), 
+       ('9', 'd8', '2022-01-20', '2032-01-20'), 
+       ('9', 'd6', '2022-01-20', '2032-01-20'), 
+       ('10', 'd6', '2022-12-20', '2032-12-20'), 
+       ('10', 'd2', '2022-12-20', '2032-12-20');
+
+-- 5 employees are manager     
+INSERT INTO `dept_manager` (`emp_no`, `dept_no`, `from_date`, `to_date`)
+VALUES (1, 'd1', '2022-01-01', '2022-12-01'),
+       (2, 'd2', '2022-02-01', '2022-12-01'),
+       (3, 'd3', '2022-03-01', '2022-12-01'),
+       (4, 'd4', '2022-04-01', '2022-12-01'),
+       (5, 'd5', '2022-05-01', '2022-12-01');
+
+
+
+-- *** UPDATE ***  
+
+-- Change the name of an employee. 
+UPDATE `employees`
+SET `first_name` = 'Pedro'
+WHERE `first_name` = 'Jose' AND `last_name` = 'Torres' AND `birth_date` = '1988-10-15';
+
+--	Change the name of all departments.
+UPDATE `departments`
+SET `dept_name` = 'newDeveloper'
+WHERE `dept_no` = 'd1';
+
+UPDATE `departments`
+SET `dept_name` = 'newManager'
+WHERE `dept_no` = 'd2';
+
+UPDATE `departments`
+SET `dept_name` = 'newAnalyst'
+WHERE `dept_no` = 'd3';
+
+UPDATE `departments`
+SET `dept_name` = 'newConsultant'
+WHERE `dept_no` = 'd4';
+
+UPDATE `departments`
+SET `dept_name` = 'newDirector'
+WHERE `dept_no` = 'd5';
+
+UPDATE `departments`
+SET `dept_name` = 'newArchitect'
+WHERE `dept_no` = 'd6';
+
+UPDATE `departments`
+SET `dept_name` = 'newEngineer'
+WHERE `dept_no` = 'd7';
+
+UPDATE `departments`
+SET `dept_name` = 'newDesigner'
+WHERE `dept_no` = 'd8';
+
+UPDATE `departments`
+SET `dept_name` = 'newProgrammer'
+WHERE `dept_no` = 'd9';
+
+UPDATE `departments`
+SET `dept_name` = 'newCoordinator'
+WHERE `dept_no` = 'd10';
+
+
+
+-- *** SELECT ***  
+
+-- Select all employees with a salary greater than 20,000, you must list all employees data and the salary.
+SELECT *
+FROM `employees`
+INNER JOIN `salaries`
+ON employees.emp_no = salaries.emp_no
+WHERE `salary` > 20000;
+
+-- Select all employees with a salary below 10,000, you must list all employees data and the salary.
+SELECT *
+FROM `employees`
+INNER JOIN `salaries`
+ON employees.emp_no = salaries.emp_no
+WHERE `salary` < 10000;
+
+-- Select all employees who have a salary between 14,000 and 50,000, you must list all employees data and the salary.
+SELECT *
+FROM `employees`
+INNER JOIN `salaries`
+ON employees.emp_no = salaries.emp_no
+WHERE `salary` BETWEEN 14000 AND 50000;
+
+-- Select the total number of employees
+SELECT COUNT(*) as `totalEmployees` 
+FROM `employees`;
+
+-- Select the total number of employees who have worked in more than one department
+  SELECT COUNT(*) as `totalEmployees`
+  FROM (
+    SELECT emp_no 
+    FROM dept_emp 
+    GROUP BY emp_no 
+    HAVING COUNT(*) > 1
+  ) employees;
+
+-- Select the titles of the year 2020
+SELECT `title`, `from_date`
+FROM `titles`
+WHERE `from_date` >= '2020-01-01' AND `from_date` <= '2020-12-31';
+
+-- Select the name of all employees with capital letters
+SELECT UPPER(`first_name`) 
+FROM `employees`;
+
+-- Select the name, surname and name of the current department of each employee
+SELECT `first_name`, `last_name`, departments.dept_name 
+FROM `employees` 
+JOIN current_dept_emp 
+ON employees.emp_no = current_dept_emp.emp_no 
+JOIN `departments` 
+ON current_dept_emp.dept_no = departments.dept_no 
+
+-- Select the name, surname and number of times the employee has worked as a manager
+SELECT employees.`first_name`, employees.last_name, COUNT(*) as `totalEmployes`
+FROM `employees` JOIN dept_manager
+ON employees.emp_no  = dept_manager.emp_no
+GROUP BY employees.emp_no;
+
+-- Select the name of employees without any being repeated
+SELECT DISTINCT `first_name`
+FROM `employees`;
+
+
+
+-- *** DELETE *** 
+
+-- Delete all employees with a salary greater than 20,000
+DELETE FROM `salaries` 
+WHERE `salary` > 20000;
+
+-- Remove the department that has more employees
+DELETE FROM `departments`
+WHERE `dept_no` = (
+        SELECT `dept_no` FROM `dept_emp`
+        GROUP BY `dept_no`
+        ORDER BY count(`dept_no`) desc
+        limit 1
+);
+
+
+
+-- *** CREATE DATA BASE ****
+
+CREATE DATABASE school;
+USE school;
+
+CREATE TABLE students (
+    id_student INT NOT NULL AUTO_INCREMENT,
+    first_name VARCHAR(50) NOT NULL,
+    last_name VARCHAR(50) NOT NULL,
+    birth_date DATE NOT NULL,
+    PRIMARY KEY (id_student)
+);
+
+CREATE TABLE parents (
+    id_parent INT NOT NULL AUTO_INCREMENT,
+    id_student INT NOT NULL,
+    first_name VARCHAR(50) NOT NULL,
+    last_name VARCHAR(50) NOT NULL,
+    PRIMARY KEY (id_parent),
+    FOREIGN KEY (id_student) REFERENCES students(id_student) ON DELETE CASCADE
+);
+
+CREATE TABLE teachers (
+    id_teacher INT NOT NULL AUTO_INCREMENT,
+    first_name VARCHAR(50) NOT NULL,
+    last_name VARCHAR(50) NOT NULL,
+    PRIMARY KEY (id_teacher)
+);
+
+CREATE TABLE subjects (
+    id_subject INT NOT NULL AUTO_INCREMENT,
+    id_student INT NOT NULL,
+    name_subject VARCHAR(50) NOT NULL,
+    PRIMARY KEY (id_subject),
+    FOREIGN KEY (id_student) REFERENCES students(id_student) ON DELETE CASCADE
+);
+
+CREATE TABLE notes (
+    id_note INT NOT NULL AUTO_INCREMENT,
+    id_student INT NOT NULL,
+    id_teacher INT NOT NULL,
+    id_subject INT NOT NULL,
+    note DECIMAL(4,2) NOT NULL,
+    date_note DATE NOT NULL,
+    PRIMARY KEY (id_note),
+    FOREIGN KEY (id_student) REFERENCES students(id_student) ON DELETE CASCADE,
+    FOREIGN KEY (id_teacher) REFERENCES teachers(id_teacher) ON DELETE CASCADE,
+    FOREIGN KEY (id_subject) REFERENCES subjects(id_subject) ON DELETE CASCADE
+);
+
+
+
+