SQL UPDATE Statement
Change data with the SQL UPDATE statement: one column, several columns, calculated values, CASE, UPDATE with JOIN and safe-update habits, with MySQL output.
SQA Tools Blog
Learn testing and automation, one article at a time
Free tutorials, solved practice problems and interview prep for QA and automation engineers: Python, Playwright, Selenium, SQL, Git and more.
1,677Articles
1,141Solved Python problems
7Topics
100%Free
Latest articles
1,677 articles · page 58 of 140SQL SELECT Statement
Learn the SQL SELECT statement step by step: columns, SELECT *, calculated columns and query execution order, with sample tables and real MySQL output.
SQL INSERT INTO Statement
Add data with SQL INSERT INTO: one row, many rows, selected columns, default values, INSERT INTO SELECT and the errors you will meet, with MySQL 8.4 output.
SQL Introduction
What is SQL and why learn it? A beginner introduction to databases, tables, RDBMS, SQL vs MySQL and the five SQL command types, with real MySQL examples.
SQL Views
Learn SQL views in MySQL: CREATE VIEW, querying a view, CREATE OR REPLACE, updatable views, WITH CHECK OPTION, views for security, and view vs table.
SQL Triggers
Learn MySQL triggers step by step: BEFORE and AFTER triggers, NEW and OLD rows, audit logs, validation with SIGNAL, keeping stock in sync, and trigger pitfalls.
SQL Transactions and ACID
Learn SQL transactions in MySQL: START TRANSACTION, COMMIT, ROLLBACK, SAVEPOINT, autocommit, ACID properties and isolation levels, with a bank transfer example.
SQL Aggregate Functions
Learn SQL aggregate functions COUNT, SUM, AVG, MIN and MAX step by step: COUNT(*) vs COUNT(column), DISTINCT, NULL handling and GROUP_CONCAT, on MySQL.
SQL SELF JOIN
Learn SQL SELF JOIN step by step: join a table to itself with aliases, list employees with their managers, compare rows in the same table, find pairs, in…
SQL FULL OUTER JOIN
Learn FULL OUTER JOIN and how to write it in MySQL with LEFT JOIN, RIGHT JOIN and UNION. Find unmatched rows on both sides and compare two tables.
SQL RIGHT JOIN
Learn SQL RIGHT JOIN step by step: keep every row of the right table, find unmatched rows, and rewrite any RIGHT JOIN as a LEFT JOIN, with MySQL…
SQL LEFT JOIN
Learn SQL LEFT JOIN step by step: keep every row of the left table, find rows with no match (anti-join), counts with zero, and ON vs WHERE pitfalls,…
Preparing for a QA interview?
Take free timed mock tests with answers and explanations.