Yaroslav kazeev w2 databases

Week2/assignment/Ex2Relationships.js

@@ -0,0 +1,51 @@
+import { Client } from "pg";
+
+// Database connection configuration
+const config = {
+  host: "localhost",
+  user: "hyfuser",
+  password: "hyfpassword",
+  database: "DBassignmentW2",
+  port: 5432,
+};
+
+const client = new Client(config);
+
+async function createTables(client) {
+    const CREATE_RESEARCH_PAPERS_TABLE = `
+    CREATE TABLE IF NOT EXISTS research_papers (
+      paper_id SERIAL PRIMARY KEY,
+      paper_title VARCHAR(50) NOT NULL,
+      conference VARCHAR(50),
+      publish_date DATE
+    )`;
+
+  const CREATE_PAPER_AUTHORS_TABLE = `
+    CREATE TABLE IF NOT EXISTS paper_authors (
+      paper_id INTEGER NOT NULL,
+      author_id INTEGER NOT NULL,
+      PRIMARY KEY (paper_id, author_id),
+      CONSTRAINT fk_paper
+        FOREIGN KEY (paper_id) 
+        REFERENCES research_papers(paper_id) 
+        ON DELETE CASCADE,
+      CONSTRAINT fk_author
+        FOREIGN KEY (author_id) 
+        REFERENCES authors(author_id) 
+        ON DELETE CASCADE
+    )`;
+
+  try {
+    await client.connect();
+    console.log("Connected to PostgreSQL database!");
+
+    // Create tables
+    await client.query(CREATE_RESEARCH_PAPERS_TABLE);
+    await client.query(CREATE_PAPER_AUTHORS_TABLE);
+  } catch (error) {
+    console.error("Error creating tables:", error);
+  } finally {
+    await client.end();
+  }
+}
+createTables(client);

Week2/assignment/Ex3AddInfo&Joins.js

@@ -0,0 +1,162 @@
+import { Client } from "pg";
+import { authors, researchPapers, paperAuthors } from "./generateSampleData.js";
+
+// Database connection configuration
+const config = {
+  host: "localhost",
+  user: "hyfuser",
+  password: "hyfpassword",
+  database: "DBassignmentW2",
+  port: 5432,
+};
+
+const client = new Client(config);
+let queryRes;
+
+async function insertAuthors(client) {
+  try {
+    // Insert authors with mentors
+    for (let i = 0; i < authors.length; i++) {
+      const author = authors[i];
+      // Set mentor to null for the first 5 authors (they will be mentors)
+      // Others will have a random mentor from the first 5 authors
+      const mentorId = i < 5 ? null : Math.floor(Math.random() * 5) + 1;
+
+      const query = {
+        text: `
+          INSERT INTO authors (author_name, university, date_of_birth, h_index, gender, mentor)
+          VALUES ($1, $2, $3, $4, $5, $6)
+          RETURNING author_id
+        `,
+        values: [
+          author.name,
+          author.university,
+          author.dob,
+          author.hIndex,
+          author.gender,
+          mentorId,
+        ],
+      };
+
+      const result = await client.query(query);
+      console.log(
+        `Inserted author: ${author.name} with ID: ${result.rows[0].author_id}`
+      );
+    }
+    console.log("All authors inserted successfully");
+  } catch (error) {
+    console.error("Error inserting authors:", error);
+    throw error;
+  }
+}
+
+async function insertResearchPapers(client) {
+  try {
+    for (const paper of researchPapers) {
+      const query = {
+        text: `
+          INSERT INTO research_papers (paper_title, conference, publish_date)
+          VALUES ($1, $2, $3)
+          RETURNING paper_id
+        `,
+        values: [paper.title, paper.conference, paper.date],
+      };
+
+      const result = await client.query(query);
+      console.log(
+        `Inserted paper: ${paper.title} with ID: ${result.rows[0].paper_id}`
+      );
+    }
+    console.log("All research papers inserted successfully");
+  } catch (error) {
+    console.error("Error inserting research papers:", error);
+    throw error;
+  }
+}
+
+async function insertPaperAuthors(client) {
+  try {
+    for (const paperAuthor of paperAuthors) {
+      const query = {
+        text: `
+          INSERT INTO paper_authors (paper_id, author_id)
+          VALUES ($1, $2)
+          ON CONFLICT DO NOTHING
+        `,
+        values: [paperAuthor.paper_id, paperAuthor.authorId],
+      };
+
+      await client.query(query);
+      console.log(
+        `Linked paper ${paperAuthor.paper_id} with author ${paperAuthor.authorId}`
+      );
+    }
+    console.log("All paper-author relationships inserted successfully");
+  } catch (error) {
+    console.error("Error inserting paper-author relationships:", error);
+    throw error;
+  }
+}
+
+async function seedDatabase(client) {
+  try {
+    await client.connect();
+    console.log("Connected to PostgreSQL database!");
+
+    // Insert new data
+    await insertAuthors(client);
+    await insertResearchPapers(client);
+    await insertPaperAuthors(client);
+
+    // Create a view for all authors and their corresponding mentors
+    const CREATE_AUTHOR_MENTOR_VIEW = `
+      CREATE OR REPLACE VIEW author_mentor AS
+      SELECT 
+        author_name,
+        mentor
+      FROM 
+        authors
+    `;
+
+    await client.query(CREATE_AUTHOR_MENTOR_VIEW);
+    // Query the view to verify it works
+    queryRes = await client.query("SELECT * FROM author_mentor");
+    console.log(
+      "\nAuthors with their mentors:",
+      JSON.stringify(queryRes.rows, null, 2)
+    );
+
+    // Create a view for all the vegetarian recipes with potatoes
+    const CREATE_AUTHORS_PAPERS_VIEW = `
+      CREATE OR REPLACE VIEW authors_papers AS
+      SELECT 
+        a.author_name,
+        rp.paper_title
+      FROM 
+        authors a
+        LEFT JOIN paper_authors pa ON a.author_id = pa.author_id
+        LEFT JOIN research_papers rp ON pa.paper_id = rp.paper_id
+    `;
+
+    await client.query(CREATE_AUTHORS_PAPERS_VIEW);
+    // Query the view to verify it works
+    queryRes = await client.query("SELECT * FROM authors_papers");
+    if (queryRes.rows.length !== 0) {
+      console.log(
+        "\nAuthors with their papers:",
+        JSON.stringify(queryRes.rows, null, 2)
+      );
+    } else {
+      console.log("There are no papers in the database");
+    }
+
+    console.log("Database seeding completed successfully!");
+  } catch (error) {
+    console.error("Error seeding database:", error);
+  } finally {
+    await client.end();
+  }
+}
+
+// Execute the seeding function
+seedDatabase(client);

Week2/assignment/Ex4AggregateFunctions.js

@@ -0,0 +1,140 @@
+import { Client } from "pg";
+import { authors, researchPapers, paperAuthors } from "./generateSampleData.js";
+
+// Database connection configuration
+const config = {
+  host: "localhost",
+  user: "hyfuser",
+  password: "hyfpassword",
+  database: "DBassignmentW2",
+  port: 5432,
+};
+
+const client = new Client(config);
+let queryRes;
+
+async function createDBviews(client) {
+  try {
+    await client.connect();
+    console.log("Connected to PostgreSQL database!");
+
+    // Create a view for all research papers and the number of authors that wrote that paper.
+    const CREATE_AUTHOR_QUANTITY_VIEW = `
+      CREATE OR REPLACE VIEW paper_authors_qty AS
+      SELECT 
+        paper_title,
+        COUNT(pa.author_id) as number_of_authors
+      FROM
+        research_papers rp
+        JOIN paper_authors pa ON rp.paper_id = pa.paper_id
+        GROUP BY paper_title
+    `;
+
+    await client.query(CREATE_AUTHOR_QUANTITY_VIEW);
+
+    queryRes = await client.query("SELECT * FROM paper_authors_qty");
+    console.log(
+      "\nResearch papers and the number of their authors:",
+      JSON.stringify(queryRes.rows, null, 2)
+    );
+
+    // Create a view for the sum of the research papers published by all female authors.
+    const CREATE_FEMALE_PAPER_NUMBER_VIEW = `
+      CREATE OR REPLACE VIEW female_paper_number AS
+        SELECT 
+          COUNT(DISTINCT rp.paper_id) as publications_sum
+        FROM
+          research_papers rp
+          JOIN paper_authors pa ON rp.paper_id = pa.paper_id
+          JOIN authors a ON a.author_id = pa.author_id
+        WHERE a.gender = 'Female'
+    `;
+
+    await client.query(CREATE_FEMALE_PAPER_NUMBER_VIEW);
+
+    queryRes = await client.query("SELECT * FROM female_paper_number");
+    console.log(
+      "\nThe sum of the research papers published by all female authors:",
+      JSON.stringify(queryRes.rows, null, 2)
+    );
+
+    // Create a view for Average of the h-index of all authors per university.
+    const CREATE_HINDEX_VIEW = `
+      CREATE OR REPLACE VIEW h_index AS
+        SELECT
+          university,
+          AVG(h_index) as average_h_index
+        FROM authors
+        GROUP BY university
+    `;
+
+    await client.query(CREATE_HINDEX_VIEW);
+    queryRes = await client.query("SELECT * FROM h_index");
+    console.log(
+      "\nThe average of the h-index of all authors per university:",
+      JSON.stringify(queryRes.rows, null, 2)
+    );
+
+    // Create a view for the sum of the research papers per university.
+    const CREATE_PAPERS_PER_UNIVERSITY_VIEW = `
+      CREATE OR REPLACE VIEW papers_per_university AS
+        SELECT
+          a.university,
+          COUNT(DISTINCT rp.paper_id) as university_publications
+        FROM authors a
+        JOIN paper_authors pa ON pa.author_id = a.author_id
+        JOIN research_papers rp ON rp.paper_id = pa.paper_id
+        GROUP BY a.university
+    `;
+
+    await client.query(CREATE_PAPERS_PER_UNIVERSITY_VIEW);
+    queryRes = await client.query("SELECT * FROM papers_per_university");
+    console.log(
+      "\nThe sum of the research papers per university:",
+      JSON.stringify(queryRes.rows, null, 2)
+    );
+
+    // Create a view for minimum of the h-index of all authors per university.
+    const CREATE_HINDEX_MIN_VIEW = `
+      CREATE OR REPLACE VIEW h_index_min AS
+        SELECT
+          university,
+          MIN(h_index) as min_h_index
+        FROM authors
+        GROUP BY university
+    `;
+
+    await client.query(CREATE_HINDEX_MIN_VIEW);
+    queryRes = await client.query("SELECT * FROM h_index_min");
+    console.log(
+      "\nThe minimum of the h-index of all authors per university:",
+      JSON.stringify(queryRes.rows, null, 2)
+    );
+
+    // Create a view for maximum of the h-index of all authors per university.
+    const CREATE_HINDEX_MAX_VIEW = `
+      CREATE OR REPLACE VIEW h_index_max AS
+        SELECT
+          university,
+          MAX(h_index) as max_h_index
+        FROM authors
+        GROUP BY university
+    `;
+
+    await client.query(CREATE_HINDEX_MAX_VIEW);
+    queryRes = await client.query("SELECT * FROM h_index_max");
+    console.log(
+      "\nThe maximum of the h-index of all authors per university:",
+      JSON.stringify(queryRes.rows, null, 2)
+    );
+
+    console.log("Database seeding completed successfully!");
+  } catch (error) {
+    console.error("Error seeding database:", error);
+  } finally {
+    await client.end();
+  }
+}
+
+// Execute the seeding function
+createDBviews(client);