SQL Tutorials

Learn how to use DECODE() in Oracle for conditional logic in data transformation. Compare DECODE() to the CASE WHEN statement in performance and behavior.

Discover how OLAP (Online Analytical Processing) enhances data analysis by providing rapid, multidimensional exploration for informed business decision-making.

Enhance your SQL skills with the SQL PIVOT operator. Learn to convert rows into columns to create pivot tables in SQL Server and Oracle.

Discover the power of the SQL SUM() function for data aggregation. Learn how to implement rolling sums, cumulative sums, and sum multiple columns effectively.

Discover the output and performance differences between UNION and UNION ALL: UNION removes duplicates while UNION ALL includes them.

Learn the application of the SQL REPLACE() function in text manipulation. Understand the use of the REPLACE() function in data cleaning and database management.

Learn how to use the SQL EXISTS() operator for subquery evaluation and filtering, complete with examples, best practices, and tips for optimizing your queries.

Learn the application of the SQL LIMIT clause to filter data. Master the use of the LIMIT clause in PostgreSQL and MySQL databases.

Explore how the LAG() function allows you to access previous rows in your dataset, enabling time series analysis and comparisons of sequential observations.

The SQL BETWEEN operator helps filter values within specific ranges, enabling efficient data analysis. Discover its various applications and full potential.

The SQL IN operator allows you to filter query results to include only rows that meet specified conditions. Explore its full potential and alternatives.

Master the SQL OFFSET clause. Discover how to use ORDER BY and LIMIT to return values based on position, with practical examples, including data pagination for web applications.