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Types of Databases

Types of Databases (RDBMS vs NoSQL) – Automation Tester Awareness​

As an automation tester, you don’t need to master every database type. You must understand which type your application uses and how that affects validation.

Most enterprise applications use Relational Databases (RDBMS). NoSQL knowledge is mainly awareness-level for testers.

High-Level Database Classification​

Databases are broadly classified into:

  1. Relational Databases (RDBMS) ⭐ (MOST IMPORTANT)
  2. Non-Relational Databases (NoSQL) (Awareness)

1️⃣ Relational Databases (RDBMS)​

RDBMS store data in tables with rows and columns and enforce relationships using keys.

Examples​

  • Oracle
  • MySQL
  • PostgreSQL
  • SQL Server

Key Characteristics of RDBMS​

  • Data stored in tables
  • Fixed schema (structure)
  • Uses SQL
  • Supports joins
  • Enforces data integrity (PK/FK)

This matches most banking, e‑commerce, enterprise systems.

Why RDBMS is Critical for Automation Testers​

As a tester, you will:

  • Validate UI/API data against DB tables
  • Write SELECT queries
  • Use joins to verify relationships
  • Check transactional data

👉 90% of DB validations in automation are on RDBMS

2️⃣ Non-Relational Databases (NoSQL) – Awareness Only​

NoSQL databases store data in non-tabular formats.

Common NoSQL Types​

TypeExample
DocumentMongoDB
Key-ValueRedis
ColumnCassandra
GraphNeo4j

How NoSQL Differs from RDBMS​

AspectRDBMSNoSQL
StructureTablesDocuments / Key-Value
SchemaFixedFlexible
Query LanguageSQLDB-specific
JoinsYesLimited / None
TransactionsStrongLimited (varies)

Tester Perspective on NoSQL​

  • Rarely queried directly in UI automation
  • Common in:
    • Microservices
    • Caching layers
    • Logs & analytics

Tester role:

  • Validate API responses
  • Validate business behavior
  • DB-level checks usually done by backend tests

How to Identify DB Type in a Project​

You can identify DB type by:

  • Asking developers
  • Checking configuration files
  • Observing SQL usage
  • Error messages (Oracle / MySQL hints)

Common Tester Mistakes ❌​

  • Expecting SQL joins in NoSQL
  • Treating all databases the same
  • Over-learning NoSQL without need
  • Writing complex queries without understanding DB type

Key Takeaways​

  • RDBMS is the primary DB type for automation testing
  • SQL knowledge is essential
  • NoSQL is awareness-level for most testers
  • Always confirm DB type before validation