Category: SQL Tutorial

Here is a clear, practical, and complete guide to the SQL GROUP BY statement, with examples, rules, and common pitfalls.  What SQL GROUP BY statement Does GROUP BY groups rows that share the same...

Here is a clear, practical guide to the SQL UNION operator, with examples, rules, and best-practice notes. What SQL UNION operator Does UNION combines the result sets of two or more SELECT statements into...

Here is a clear, complete, and practical guide to SQL JOINs, including diagrams, examples, and best-practice notes.    What Are SQL JOINs? SQL JOINs combine rows from two or more tables based on a...

Here is a clear, practical guide to SQL Aliases, how they work, and when you should use them. Aliases make queries shorter, cleaner, and easier to read. What Are SQL Aliases? SQL aliases create...

Here is a clear and practical guide to the SQL BETWEEN operator, with examples for numbers, dates, text, and best-practice notes. What the SQL BETWEEN operator Does BETWEEN is used to filter values within...

Here is a clear and practical guide to the SQL IN operator, with examples, performance notes, and best practices. What the SQL IN operator Does IN allows you to test whether a value matches...

Here is a clear and complete guide to SQL Wildcards, how they work, and how to use them effectively in pattern matching queries.  What Are SQL Wildcards? Wildcards are special characters used with the...

Here is a clean and practical guide to the SQL LIKE operator, with patterns, examples, and best practices for different SQL engines.  What the SQL LIKE operator Does LIKE is used in SQL to...

SQL AVG function – Complete Guide In SQL AVG function is an aggregate function used to calculate the average (mean) of numeric values in a column.  1. Basic Syntax (Beginner)

   Works only on...

Here is a clear, practical guide to the SQL SUM function, with examples, behavior notes, and best practices.  What SQL SUM function Does SUM() returns the total of all non-NULL numeric values in a column....