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SQL & Databases

Database Foundations4

SQL Fundamentals5

Joins & Aggregation5

Design & Normalization4

Transactions & Performance4

ACID and transactions: the four promises every database makes
Concurrency and isolation levels
Query execution and EXPLAIN: seeing what the database actually does
Performance tuning, hands-on: fixing a genuinely slow query

PostgreSQL Deep Dive4

MySQL & MariaDB4

NoSQL & Choosing the Right Database5

Advanced SQL Toolkit5

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SQL & Databases

Database Foundations4

SQL Fundamentals5

Joins & Aggregation5

Design & Normalization4

Transactions & Performance4

ACID and transactions: the four promises every database makes
Concurrency and isolation levels
Query execution and EXPLAIN: seeing what the database actually does
Performance tuning, hands-on: fixing a genuinely slow query

PostgreSQL Deep Dive4

MySQL & MariaDB4

NoSQL & Choosing the Right Database5

Advanced SQL Toolkit5

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ACID and transactions: the four promises every database makes

What a transaction actually is, and the precise meaning of Atomicity, Consistency, Isolation and Durability.

12 min readUpdated 2026-09-04transactionsacidconcurrency