If the Oracle SQL Developer crashing on startup on your computer, you can follow the solutions mentioned in this post to resolve the issue.

Using Oracle Developer to work on your Oracle SQL database presents you with a functional IDE to write code and check data outputs from queries.

The SQL development environment helps the programmer perform basic functions on supported non-Oracle databases. Developers can browse and execute basic SELECT queries on supported databases.

SQL Server has an optimizer that usually does a great job of optimizing code for the most effective execution. A query execution plan is the breakdown of how the optimizer will run (or ran) a query.

Salesforce.com has open sourced Phoenix, a Java layer enabling developers to run SQL queries on Apache HBase. Update: An interview on Phoenix with James Taylor, Lead Developer at Salesforce.com ...

If you want to install Oracle SQL Developer on your Windows computer for free, check if you meet the requirements and then go through the instructions mentioned here.

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