GuideTechnology
8 min read
Put the whole backend together: the final architecture, the requirements checklist, how each article contributed, how to build, run and test it, an honest list of limitations, and the questions an interviewer is likely to ask about it.
GuideTechnology
29 min read
Replace the in-memory repository with a real PostgreSQL database using JPA, Hibernate and Spring Data: map an entity, manage the schema with Flyway migrations, understand the persistence context and dirty checking, write queries, and read the SQL Hibernate actually generates, including a real failure only PostgreSQL revealed.
GuideTechnology
30 min read
Take the Expense Tracker CLI and add a PostgreSQL repository behind the same interface: an idempotent schema, a transactional bulk import, a connection pool, one shared contract test for every implementation, a fat jar, and an honest review.
GuideTechnology
25 min read
Learn JDBC, the standard way Java programs use a relational database: connecting with a driver, running queries with PreparedStatement, mapping rows, preventing SQL injection, transactions, error codes, batching and connection pooling, with every program run against PostgreSQL 18.
GuideTechnology
21 min read
Learn the SQL that backend developers use every day on PostgreSQL: tables and constraints, inserting, querying, joining and grouping data, transactions and isolation, indexes and query plans, and normalisation, with every statement run on a real PostgreSQL server.
