PostgreSQL connection with pg in Node.js - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the 'pg' library in Node.js?

The 'pg' library allows Node.js applications to connect and interact with PostgreSQL databases easily.

beginner

How do you create a new client connection using 'pg'?

You create a new client by importing { Client } from 'pg' and then creating an instance with connection details like user, host, database, password, and port.

beginner

Why should you call client.connect() before running queries?

Calling client.connect() establishes the connection to the PostgreSQL server so queries can be sent and results received.

beginner

What method do you use to run a SQL query with 'pg' client?

Use client.query(sqlText, values) to run SQL commands. It returns a promise with the query result.

beginner

How do you properly close a PostgreSQL connection using 'pg'?

Call client.end() to close the connection and free resources after finishing database operations.

Which import statement is correct to use the Client class from 'pg'?

A import { Client } from 'pg';

B const Client = require('pg');

C import Client from 'pg/client';

D const { Client } = require('pg/client');

The correct modern ES module import is 'import { Client } from 'pg';'.

What is the first step after creating a new Client instance?

A Run client.query() immediately

B Call client.connect() to open the connection

C Call client.end() to close connection

D Import pg again

You must call client.connect() to establish the connection before running queries.

How do you pass parameters safely to a SQL query using 'pg'?

A Use parameterized queries with placeholders and values array

B Concatenate strings directly

C Use template literals without placeholders

D Use client.query without parameters

Parameterized queries prevent SQL injection by using placeholders ($1, $2) and passing values separately.

What does client.query() return?

A Nothing

B A callback function

C A boolean value

D A promise that resolves with query results

client.query() returns a promise that resolves to the query result object.

Which method closes the database connection?

A client.disconnect()

B client.close()

C client.end()

D client.stop()

client.end() properly closes the connection to the PostgreSQL server.

Explain the steps to connect to a PostgreSQL database using the 'pg' library in Node.js.

Think about setup, connection, querying, and cleanup.

Describe how to safely run a SQL query with parameters using 'pg'.

Focus on parameterized queries and security.