Jassif Team Institution

let mysql = require('mysql');

let con = mysql.createConnection({
  host: "localhost",
  user: "yourusername",
  password: "yourpassword",
  database: "mydb"
});

con.connect(function(err) {
  if (err) throw err;
  let sql = "DROP TABLE customers";
  con.query(sql, function (err, result) {
    if (err) throw err;
    console.log("Table deleted");
  });
});

C:\Users\Your Name>node demo_db_drop_table.js

Table deleted

let mysql = require('mysql');

let con = mysql.createConnection({
  host: "localhost",
  user: "yourusername",
  password: "yourpassword",
  database: "mydb"
});

con.connect(function(err) {
  if (err) throw err;
  let sql = "DROP TABLE IF EXISTS customers";
  con.query(sql, function (err, result) {
    if (err) throw err;
    console.log(result);
  });
});

C:\Users\Your Name>node demo_db_drop_table_if.js

{
  fieldCount: 0,
  affectedRows: 0,
  insertId: 0,
  serverStatus: 2,
  warningCount: 0,
  message: '',
  protocol41: true,
  changedRows: 0
}

{
  fieldCount: 0,
  affectedRows: 0,
  insertId: 0,
  serverStatus: 2,
  warningCount: 1,
  message: '',
  protocol41: true,
  changedRows: 0
}

// Drop multiple tables
let sql = "DROP TABLE customers, orders, products";
con.query(sql, function (err, result) {
  if (err) throw err;
  console.log("Multiple tables deleted");
});

// Drop multiple tables with IF EXISTS
let sql = "DROP TABLE IF EXISTS customers, orders, products";
con.query(sql, function (err, result) {
  if (err) throw err;
  console.log("Tables deleted if they existed");
});

// Check if table exists before dropping
con.query("SHOW TABLES LIKE 'customers'", function (err, result) {
  if (err) throw err;
  
  if (result.length > 0) {
    console.log("Table exists, proceeding with drop...");
    
    // Drop the table
    con.query("DROP TABLE customers", function (err, dropResult) {
      if (err) throw err;
      console.log("Table dropped successfully");
    });
  } else {
    console.log("Table does not exist, no action needed");
  }
});

// Safe drop with transaction
con.beginTransaction(function(err) {
  if (err) throw err;
  
  // First create backup or log the action
  let logSql = "INSERT INTO drop_log (table_name, dropped_at) VALUES (?, NOW())";
  con.query(logSql, ['customers'], function (err, logResult) {
    if (err) {
      return con.rollback(function() {
        throw err;
      });
    }
    
    // Then drop the table
    let dropSql = "DROP TABLE IF EXISTS customers";
    con.query(dropSql, function (err, dropResult) {
      if (err) {
        return con.rollback(function() {
          throw err;
        });
      }
      
      console.log("Table dropped with logging");
      
      // Commit the transaction
      con.commit(function(err) {
        if (err) {
          return con.rollback(function() {
            throw err;
          });
        }
        console.log("Transaction completed successfully");
      });
    });
  });
});

const mysql = require('mysql');

// Create connection
const con = mysql.createConnection({
  host: "localhost",
  user: "root",
  password: "password",
  database: "company_db"
});

// Connect to MySQL
con.connect((err) => {
  if (err) {
    console.error('Error connecting to MySQL:', err.message);
    return;
  }
  
  console.log('Connected to MySQL database');
  
  // Example 1: Basic DROP TABLE
  console.log('\n1. Basic DROP TABLE:');
  con.query("DROP TABLE IF EXISTS temp_table", (err, result) => {
    if (err) {
      console.error('Error in drop 1:', err.message);
      return;
    }
    console.log('Basic drop result:', result);
  });
  
  // Example 2: Safe drop with existence check
  console.log('\n2. Safe drop with check:');
  const tableName = 'customers';
  
  // First check if table exists
  con.query("SHOW TABLES LIKE ?", [tableName], (err, checkResult) => {
    if (err) {
      console.error('Error checking table existence:', err.message);
      return;
    }
    
    if (checkResult.length > 0) {
      console.log(`Table '${tableName}' exists, proceeding with drop...`);
      
      // Drop the table with IF EXISTS for safety
      con.query("DROP TABLE IF EXISTS ?", [tableName], (err, dropResult) => {
        if (err) {
          console.error('Error dropping table:', err.message);
          return;
        }
        
        console.log('Table dropped successfully');
        console.log('Drop result:', dropResult);
      });
    } else {
      console.log(`Table '${tableName}' does not exist`);
    }
  });
  
  // Example 3: Multiple table drop
  console.log('\n3. Multiple table drop:');
  setTimeout(() => {
    const tables = ['backup_customers', 'temp_orders', 'old_products'];
    
    tables.forEach((table, index) => {
      con.query("DROP TABLE IF EXISTS ??", [table], (err, result) => {
        if (err) {
          console.error(`Error dropping table ${table}:`, err.message);
          return;
        }
        
        if (result.warningCount > 0) {
          console.log(`Table '${table}' did not exist (warning count: ${result.warningCount})`);
        } else {
          console.log(`Table '${table}' dropped successfully`);
        }
        
        // Close connection after last operation
        if (index === tables.length - 1) {
          setTimeout(() => {
            con.end((err) => {
              if (err) {
                console.error('Error closing connection:', err.message);
                return;
              }
              console.log('\nConnection closed');
            });
          }, 1000);
        }
      });
    });
  }, 2000);
});