Writing complex SQL queries can be challenging, but there are several tips and best practices that can help you write effective and efficient queries:

1. Start with a clear understanding of the data and the problem you are trying to solve. This will help you determine the specific requirements for your query and ensure that you are writing a query that will return the right results.

2. Break down your query into smaller, more manageable pieces. This will make it easier to write and test your query, and will also help you identify any issues or errors in your SQL syntax.

3. Use subqueries and common table expressions (CTEs) to structure and organize your query. This will help you avoid writing overly complex queries, and will also make it easier to read and understand your query.

4. Use aliases and other techniques to make your query more readable and self-explanatory. This will help other people who may need to read or work with your query in the future.

5. Test your query thoroughly to ensure that it returns the expected results. This will help you identify and fix any issues with your query, and will also help you optimize the performance of your query.

Overall, writing complex SQL queries requires a combination of knowledge, experience, and practice. By following these tips and best practices, you can write effective and efficient queries that meet the needs of your application and your users.

There are many tools available that can help you write SQL queries more effectively and efficiently. Some common examples include:

1. Query editors and IDEs: Many database management systems, such as MySQL and Microsoft SQL Server, include a built-in query editor or integrated development environment (IDE) that can help you write, test, and optimize your SQL queries. These tools often include features like syntax highlighting, code completion, and debugging tools that can make it easier to write and test your queries.

2. Online query builders: There are many online tools and services, such as SQL Fiddle and db-fiddle, that allow you to build and test SQL queries using a web-based interface. These tools can be especially useful if you don’t have access to a specific database management system, or if you want to test your queries against different database engines.

3. Code generation tools: Some tools, such as SQL Power Architect, can generate SQL code automatically based on the structure of your database or the data you want to query. These tools can be useful if you need to generate complex SQL queries quickly, or if you want to experiment with different query structures and optimization strategies.

Overall, the best SQL query writing tool for you will depend on your specific needs and preferences. Some tools may be better suited for writing simple queries, while others may be more suitable for complex or performance-critical queries. It’s important to choose a tool that suits your needs and that you are comfortable using.