querygen

QueryGen

QueryGen is a dynamic SQL query builder and database management library supporting SQLite, MySQL, and PostgreSQL. It provides a simple yet powerful API to construct and execute queries programmatically, making database interactions seamless and maintainable.

Features

Support for multiple databases: SQLite, MySQL, and PostgreSQL.

Chainable API for building complex SQL queries.

Dynamic query generation with parameterized inputs for security.

Lightweight and modular design.

Installation

Install the library via npm:

npm install querygen

Usage

Setup

To use QueryGen, import and configure it with your preferred database type and connection details.

import { DatabaseManager } from 'querygen';

// Connection details for supported databases const dbType: 'sqlite' | 'mysql' | 'postgres' = 'mysql'; const connectionString = { host: 'localhost', user: 'root', password: 'your_password', database: 'your_database', };

const databaseManager = new DatabaseManager(dbType, connectionString);

Building Queries

Use the QueryBuilder to construct SQL queries programmatically:

import { QueryBuilder } from 'querygen';

const queryBuilder = new QueryBuilder() .table('users') .select(['id', 'name']) .where('age > ?', 18) .where('status = ?', 'active');

const { query, params } = queryBuilder.build(); console.log('Generated Query:', query); // SELECT id, name FROM users WHERE age > ? AND status = ? console.log('Query Parameters:', params); // [18, 'active']

Executing Queries

Once you build a query, execute it using the DatabaseManager:

async function fetchActiveUsers() { try { await databaseManager.connect(); const { query, params } = queryBuilder.build(); const results = await databaseManager.executeQuery(query, params); console.log('Query Results:', results); } catch (error) { console.error('Error:', error); } finally { await databaseManager.disconnect(); } }

fetchActiveUsers();

API Documentation

QueryBuilder

Methods

table(tableName: string): QueryBuilder

Specifies the table for the query.

select(fields: string[]): QueryBuilder

Specifies the fields to select. Defaults to * if not provided.

where(condition: string, param?: any): QueryBuilder

Adds a conditional clause with optional parameterization.

join(type: 'INNER' | 'LEFT' | 'RIGHT', table: string, on: string): QueryBuilder

Adds a JOIN clause.

aggregate(func: 'COUNT' | 'SUM' | 'AVG' | 'MIN' | 'MAX', field: string): QueryBuilder

Adds an aggregation function to the query.

build(): { query: string; params: any[] }

Builds the query string and returns it along with parameters.

Example

const queryBuilder = new QueryBuilder() .table('orders') .select(['id', 'total']) .where('customer_id = ?', 123) .build();

console.log(queryBuilder.query); // SELECT id, total FROM orders WHERE customer_id = ? console.log(queryBuilder.params); // [123]

DatabaseManager

Methods

constructor(dbType: 'sqlite' | 'mysql' | 'postgres', connectionString: string | object)

Initializes the database manager with the specified type and connection details.

connect(): Promise

Establishes a connection to the database.

disconnect(): Promise

Closes the database connection.

executeQuery(query: string, params: any[]): Promise<any[]>

Executes a parameterized query and returns the results.

Example

const databaseManager = new DatabaseManager('sqlite', './database.sqlite');

async function fetchProducts() { try { await databaseManager.connect(); const results = await databaseManager.executeQuery('SELECT * FROM products WHERE price > ?', [50]); console.log('Products:', results); } finally { await databaseManager.disconnect(); } }

fetchProducts();

Contributing

Contributions are welcome! Feel free to submit issues or pull requests on the GitHub repository.

License

QueryGen is licensed under the MIT License.