query-builder-sql

The SQL Query Builder is a versatile library that allows you to construct SQL queries in JavaScript. This library allows you to create parameterized queries, handle complex expressions, perform subqueries, and more.

Installation

npm i query-builder-sql

Usage

1. Create an instance of the QueryBuilder class by specifying the table name:

 const query = new QueryBuilder('table-name');

2. Chain methods to build your query:

query
 .select('order_id', 'total_amount')
 .where('status', '=', 'shipped')
 .orderBy('created_at', 'DESC')
 .groupBy('country', 'region')
 .having('SUM(total_amount)', '>', 10000)
 .join('customers', 'orders.customer_id = customers.customer_id', 'LEFT')
 .paginate(2, 10);

3. Execute the query

const sqlQuery = query.build();

Methods

• select(...columns): Specify the columns to select.
• where(column, operator, value): Add a WHERE condition.
• orderBy(column, direction): Specify the order of results.
• groupBy(...columns): Group results by specified columns.
• having(column, operator, value): Add a HAVING condition.
• join(table, onCondition, type): Add a JOIN clause.
• insert(data): Construct an INSERT INTO query.
• update(data): Construct an UPDATE query.
• delete(): Construct a DELETE query.
• commit(): Execute a COMMIT statement.
• rollback(): Execute a ROLLBACK statement.

Examples

Let’s walk through some examples of how to use the SQL Query Builder.

1. Select Query
   • Retrieve order details for shipped orders:

     const selectQuery = new QueryBuilder('orders')
       .select('order_id', 'total_amount')
       .where('status', '=', 'shipped')
       .build();
     
     console.log(selectQuery);
     // Output: SELECT order_id, total_amount FROM orders WHERE status = 'shipped'
     
     

2. Insert Query
   • Insert a new order:

     const insertQuery = new QueryBuilder('orders')
        .insert({ order_id: 123, total_amount: 500 })
     
     console.log(insertQuery);
     // Output: INSERT INTO orders (order_id, total_amount) VALUES (123, 500)
     
     

3. Update Query
   • Update the status of an order:

     const updateQuery = new QueryBuilder('orders')
       .update({ status: 'delivered' })
       .where('order_id', '=', 123)
       .build();
     
     console.log(updateQuery);
     // Output: UPDATE orders SET status = 'delivered' WHERE order_id = 123
     
     

4. Delete Query
   • Delete all cancelled orders:

      const deleteQuery = new QueryBuilder('orders')
         .delete()
         .where('status', '=', 'canceled')
         .build();
     
      console.log(deleteQuery);
      // Output: DELETE FROM orders WHERE status = 'canceled'
     
     

5. Join Query
   • Retrieve order details along with customer information:

     const joinQuery = new QueryBuilder('orders')
        .select('orders.order_id', 'orders.total_amount', 'customers.customer_name')
        .join('customers', 'orders.customer_id = customers.customer_id', 'LEFT')
        .build();
     
      console.log(joinQuery);
      // Output: SELECT orders.order_id, orders.total_amount, customers.customer_name
      //         FROM orders
      //         LEFT JOIN customers ON orders.customer_id = customers.customer_id
     
     

6. SubQuery:
   • Retrieve employees whose salary is greater than the average salary across all employees:

     const subquery = new QueryBuilder('employees')
         .select('AVG(salary)')
         .build();
     
     const mainQuery = new QueryBuilder('employees')
         .select('id', 'last_name', 'salary')
         .where('salary', '>', `(${subquery})`)
         .build();
     
     console.log(mainQuery);
     // Output: SELECT id, last_name, salary
     //         FROM employees
     //         WHERE salary > (SELECT AVG(salary) FROM employees)
     
     

Contributing

Feel free to contribute by opening issues or pull requests. Let’s make this query builder even better!