Ch 1 · PostgreSQL Connection with Node.js · PostgreSQL
Topic 1 of 3 in PostgreSQL — Complete Tutorial (Beginner) — 4 lessons.
Node.js and PostgreSQL
Connect to PostgreSQL from Node.js using the pg library. A connection pool keeps a set of reusable database connections ready, so your app does not open a new one for every request. You will also send parameterised queries, using $1 and $2 placeholders to block SQL injection, and wrap several changes in a transaction with BEGIN, COMMIT and ROLLBACK.
Node.js and PostgreSQL in Code
This Node.js example creates one shared Pool with the pg library, then runs a parameterised query where the values travel separately from the SQL text. The second half moves money between two accounts inside a transaction: if either UPDATE fails, ROLLBACK undoes both and the error is rethrown so it is not silently lost. Notice that client.release() sits in finally, so the connection always goes back to the pool, and that everything runs inside an async function, because a require-style script cannot use await at the top level.
Practice: Node.js and PostgreSQL
Now write the database code yourself in Node.js. You will set up a connection pool, run a query that uses placeholders instead of pasted-in values, and carry out a transaction that cleans up after errors. A correct answer uses $1-style parameters, calls ROLLBACK when something goes wrong and always releases the client, whether the transaction succeeds or fails.
Solution & Challenge: Node.js and PostgreSQL
Compare your code with the worked solution, which wraps the query and the transaction in reusable async functions and rethrows errors after rolling back. The challenge then asks you to build a full create, read, update and delete API with Express.js on top of PostgreSQL. A good answer shares a single pool, parameterises every query and uses transactions for multi-step operations.