SQL for Testers
SQL tutorials for testers: SELECT, joins, DDL and DML, subqueries, transactions and test data checks.
SQL String Functions: CONCAT, SUBSTRING, REPLACE, TRIM and String Problems
SQL string functions with examples, plus common string problems: validating emails, extracting domains, cleaning phone numbers, parsing and formatting names.
SQL NULL Handling: COALESCE, IFNULL, NULLIF, NOT IN Traps and COUNT(*)
How SQL handles NULL: IS NULL, COALESCE, IFNULL, NULLIF, numeric functions, and the traps behind wrong results: NOT IN with NULLs, COUNT(*) vs COUNT(col).
SQL CASE WHEN, UNION vs UNION ALL and Pivot Queries
SQL CASE WHEN with examples (categories, conditional counts), UNION vs UNION ALL, and pivoting rows into columns with CASE inside aggregate functions.
DDL Commands in SQL: CREATE, ALTER, DROP, TRUNCATE and RENAME (with Examples)
DDL commands in SQL with examples: CREATE, ALTER, DROP, TRUNCATE and RENAME, DDL vs DML vs DCL vs TCL, and why TRUNCATE can't be rolled back.
Scenario-Based SQL Questions for Testers (With Sample Answers)
Real-world SQL scenarios for QA — verifying inserts, UI vs DB validation, user-wise bug counts, foreign key checks, and manual database testing, with answers.
SQL Performance & Optimization: Query Tuning and Indexing
Learn SQL performance tuning — SQL query optimization, how indexing helps, analyzing slow queries with EXPLAIN, and database testing tools — for QA and SDET.
Common SQL Queries for Testers (Bug Counts, Test Cases & More)
Practical SQL queries for QA — count bugs in the last 7 days, find users who didn't log in, fetch test cases by module, and count bugs per developer.
Advanced SQL Concepts: Views, Indexes, Normalization, Procedures
Advanced SQL for testers: views vs tables, indexes, normalization (1NF–3NF), stored procedures, triggers and functions — with examples run on MariaDB.
SQL INSERT, UPDATE, DELETE, Transactions & ACID Explained
Learn SQL data modification — INSERT, UPDATE, DELETE with WHERE, transactions, COMMIT and ROLLBACK, and ACID properties — with clear examples.
SQL Subqueries Explained: Correlated, Nth-Highest Salary & More
Learn SQL subqueries — correlated vs non-correlated, finding the second/nth highest salary, above-average queries, and ORDER BY in subqueries.
SQL Aggregate Functions & Grouping: COUNT, SUM, GROUP BY, HAVING
Learn SQL aggregate functions — COUNT, SUM, AVG, MIN, MAX — plus GROUP BY, HAVING, and WHERE vs HAVING, with clear examples for testers.
SQL Joins Explained: INNER, LEFT, RIGHT, FULL (With Examples for Testers)
SQL joins with examples: INNER, LEFT, RIGHT and FULL JOIN, LEFT vs RIGHT JOIN, finding matching and missing records, and FULL JOIN in MySQL.
SQL SELECT & Filtering: DISTINCT, LIKE, IN, BETWEEN & NULL
Learn to filter data in SQL — SELECT, DISTINCT, LIKE wildcards, IN, BETWEEN, IS NULL vs = NULL, and aliases — with clear examples for testers.
Basic SQL Commands: DDL, DML, DCL & TCL with Examples (For Testers)
Basic SQL commands with examples: DDL, DML, DCL and TCL, DELETE vs TRUNCATE vs DROP, keys and constraints, plus the queries testers use most.