w2-aziz-databases

Week2/Joins.js

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+const mysql = require("mysql2/promise");
+
+async function executeQuery(connection, query) {
+  try {
+    const [rows] = await connection.query(query);
+    return rows;
+  } catch (error) {
+    console.error("Error executing query:", error);
+  }
+}
+
+async function main() {
+  const connection = await mysql.createConnection({
+    host: "localhost",
+    user: "hyfuser",
+    password: "hyfpassword",
+    database: "meetup",
+  });
+
+  try {
+    const authorsWithMentorsQuery = `
+      SELECT a.author_name AS Author, m.author_name AS Mentor
+      FROM authors a
+      LEFT JOIN authors m ON a.mentor = m.author_id;
+    `;
+    const authorsWithMentors = await executeQuery(
+      connection,
+      authorsWithMentorsQuery
+    );
+    console.log("Authors and their Mentors:");
+    console.table(authorsWithMentors);
+
+    // 2. Query to get all columns of authors and their published paper titles
+    const authorsWithPapersQuery = `
+      SELECT a.*, p.paper_title
+      FROM authors a
+      LEFT JOIN research_papers p ON a.author_id = p.author_id;
+    `;
+    const authorsWithPapers = await executeQuery(
+      connection,
+      authorsWithPapersQuery
+    );
+    console.log("Authors and their Published Papers:");
+    console.table(authorsWithPapers);
+  } finally {
+    await connection.end();
+    console.log("Connection closed.");
+  }
+}
+
+// Run the main function`````````````
+main();

Week2/Relationships.js

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+const mysql = require("mysql2/promise");
+
+async function executeQuery(connection, query) {
+  try {
+    await connection.query(query);
+  } catch (error) {
+    console.error("Error executing query:", error);
+  }
+}
+
+async function createAuthorsTable(connection) {
+  const createTableQuery = `
+    CREATE TABLE IF NOT EXISTS authors (
+      author_id INT AUTO_INCREMENT PRIMARY KEY,
+      author_name VARCHAR(255) NOT NULL,
+      university VARCHAR(255),
+      date_of_birth DATE,
+      h_index INT,
+      gender ENUM('Male', 'Female', 'Other'),
+      mentor INT,
+      FOREIGN KEY (mentor) REFERENCES authors(author_id)
+    );
+  `;
+  await executeQuery(connection, createTableQuery);
+  console.log("Authors table created.");
+}
+
+async function createResearchPapersTable(connection) {
+  const createTableQuery = `
+    CREATE TABLE IF NOT EXISTS research_papers (
+      paper_id INT AUTO_INCREMENT PRIMARY KEY,
+      paper_title VARCHAR(255) NOT NULL,
+      conference VARCHAR(255),
+      publish_date DATE
+    );
+  `;
+  await executeQuery(connection, createTableQuery);
+  console.log("Research papers table created.");
+}
+
+async function createResearchPaperAuthorsTable(connection) {
+  const createTableQuery = `
+    CREATE TABLE IF NOT EXISTS research_paper_authors (
+      paper_id INT,
+      author_id INT,
+      PRIMARY KEY (paper_id, author_id),
+      FOREIGN KEY (paper_id) REFERENCES research_papers(paper_id) ON DELETE CASCADE,
+      FOREIGN KEY (author_id) REFERENCES authors(author_id) ON DELETE CASCADE
+    );
+  `;
+  await executeQuery(connection, createTableQuery);
+  console.log("Research paper authors table created.");
+}
+
+async function insertSampleData(connection) {
+  const authors = [
+    ["Alice Smith", "University A", "1985-05-12", 15, "Female"],
+    ["Bob Johnson", "University B", "1978-11-22", 20, "Male"],
+    ["Carol Williams", "University C", "1990-02-17", 10, "Female"],
+    ["David Brown", "University D", "1982-03-03", 25, "Male"],
+    ["Eve Davis", "University E", "1989-07-25", 30, "Female"],
+    ["Frank Miller", "University F", "1983-09-30", 12, "Male"],
+    ["Grace Wilson", "University G", "1991-01-15", 8, "Female"],
+    ["Hank Moore", "University H", "1975-12-05", 22, "Male"],
+    ["Ivy Taylor", "University I", "1987-06-14", 18, "Female"],
+    ["Jack Anderson", "University J", "1980-10-01", 16, "Male"],
+    ["Kathy Thomas", "University K", "1992-04-21", 5, "Female"],
+    ["Liam Jackson", "University L", "1986-08-11", 14, "Male"],
+    ["Mia White", "University M", "1993-05-19", 7, "Female"],
+    ["Noah Harris", "University N", "1984-03-12", 20, "Male"],
+    ["Olivia Martin", "University O", "1990-11-30", 15, "Female"],
+  ];
+
+  const insertAuthorsQuery = `
+    INSERT INTO authors (author_name, university, date_of_birth, h_index, gender)
+    VALUES ?;
+  `;
+
+  await connection.query(insertAuthorsQuery, [authors]);
+
+  // Insert research papers
+  const papers = [];
+  for (let i = 1; i <= 30; i++) {
+    papers.push([`Research Paper ${i}`, `Conference ${i}`, `2023-01-${i}`]);
+  }
+
+  const insertPapersQuery = `
+    INSERT INTO research_papers (paper_title, conference, publish_date)
+    VALUES ?;
+  `;
+
+  await connection.query(insertPapersQuery, [papers]);
+
+  // Insert into research_paper_authors table
+  const paperAuthors = [];
+  for (let i = 1; i <= 30; i++) {
+    const numAuthors = Math.floor(Math.random() * 3) + 1; // Random number of authors per paper (1 to 3)
+    for (let j = 0; j < numAuthors; j++) {
+      const authorId = Math.floor(Math.random() * 15) + 1; // Random author_id between 1 and 15
+      paperAuthors.push([i, authorId]);
+    }
+  }
+
+  const insertPaperAuthorsQuery = `
+    INSERT INTO research_paper_authors (paper_id, author_id)
+    VALUES ?;
+  `;
+  await connection.query(insertPaperAuthorsQuery, [paperAuthors]);
+
+  console.log("Sample data inserted.");
+}
+
+async function main() {
+  const connection = await mysql.createConnection({
+    host: "localhost",
+    user: "hyfuser",
+    password: "hyfpassword",
+    database: "meetup",
+  });
+
+  try {
+    await createAuthorsTable(connection);
+    await createResearchPapersTable(connection);
+    await createResearchPaperAuthorsTable(connection);
+    await insertSampleData(connection);
+  } finally {
+    await connection.end();
+    console.log("Connection closed.");
+  }
+}
+
+main();

Week2/keys.js

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+const mysql = require("mysql2/promise");
+
+async function executeQuery(connection, query) {
+  try {
+    await connection.query(query);
+  } catch (error) {
+    console.error("Error executing query:", error);
+  }
+}
+
+async function main() {
+  const connection = await mysql.createConnection({
+    host: "localhost",
+    user: "hyfuser",
+    password: "hyfpassword",
+    database: "meetup",
+  });
+
+  try {
+    // Step 1: Create the authors table
+    const createTableQuery = `
+      CREATE TABLE IF NOT EXISTS authors (
+        author_id INT AUTO_INCREMENT PRIMARY KEY,
+        author_name VARCHAR(255) NOT NULL,
+        university VARCHAR(255),
+        date_of_birth DATE,
+        h_index INT,
+        gender ENUM('Male', 'Female', 'Other')
+      );
+    `;
+    await executeQuery(connection, createTableQuery);
+    console.log("Authors table created.");
+
+    // Step 2: Check if the mentor column exists before adding it
+    const checkColumnQuery = `
+      SELECT COUNT(*) AS count 
+      FROM information_schema.COLUMNS 
+      WHERE TABLE_NAME = 'authors' 
+        AND COLUMN_NAME = 'mentor';
+    `;
+    const [rows] = await connection.query(checkColumnQuery);
+
+    if (rows[0].count === 0) {
+      // Step 3: Add the mentor column with foreign key constraint
+      const addMentorColumnQuery = `
+        ALTER TABLE authors
+        ADD COLUMN mentor INT,
+        ADD CONSTRAINT fk_mentor
+        FOREIGN KEY (mentor) REFERENCES authors(author_id);
+      `;
+      await executeQuery(connection, addMentorColumnQuery);
+      console.log("Mentor column added with foreign key constraint.");
+    } else {
+      console.log("Mentor column already exists. Skipping addition.");
+    }
+  } finally {
+    await connection.end();
+    console.log("Connection closed.");
+  }
+}
+
+// Run the main function
+main();