Read this SQL tutorial to learn when to use SELECT, JOIN, subselects and UNION to access multiple tables with a single statement.

Many people are confused by various JOIN operations supported by SQL. Learn to master the SQL command line with this crash course in JOIN syntax.

Follow this step-by-step guide to install PostgreSQL, load data, connect to a database, and execute SQL queries including table joins ...

SQL Server 2016 lets you treat JSON objects like rows in a table, allowing you to use data from AJAX queries in joins, updates and any other SQL statement you can think of.

Analyze database contents using basic, intermediate and advanced SQL statement syntax and usage. Demonstrate capability to query data from multiple tables using SQL JOINS. Create and modify database ...

At the time, CockroachDB had three large deficits, in my opinion: Limited optimization of SQL JOIN queries, no fully managed service, and no support for JSON or Protobuf data types.