SQL Tutorials

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.

The SQL MINUS operator subtracts one result set from another. It is simple to use: Just place MINUS between two queries to exclude common records from the first set.

Learn how to query and filter a date greater than a specific date in SQL. Compare how the date greater than logic differs in MySQL, PostgreSQL, and SQL Server.

Integrity constraints in SQL are rules enforced on database tables to maintain data accuracy, consistency, and validity, such as ensuring unique primary keys and valid foreign key relationships.

The ROW_NUMBER() SQL function assigns sequential integers to rows within a result set, optionally partitioning the data and ordering the rows within each partition.

Review three methods to add comments in SQL: single-line comments, multiline comments, and inline comments using the following syntax: --, /*, and */.

Learn about NoSQL databases - why NoSQL, how they differ from relational databases, the different types, and design your own NoSQL database using MongoDB.