When Should I Use SQL Joins vs. Subqueries?

In general, prefer using joins. They make combining multiple tables straightforward. But if you’re working with Microsoft SQL Server, keep in mind that Common Table Expressions (CTEs) can help too. Just watch out for issues with correlated subqueries in stored procedures—they can slow things down or lead to data inconsistencies during concurrent updates.

If your tables are related by a foreign key and you can directly map them to the output you need, go with a JOIN. It's typically cleaner and more efficient. Otherwise, a subquery can be useful if you need to create a relation that doesn't neatly fit into your output from just one table.

Have you tried searching for it? I found a helpful Stack Overflow post just by googling your question. Maybe add more detail or an example about what's confusing you.

As a rule of thumb, if you need to combine columns from different tables, go for JOINs. But if your result depends on multiple tables but only involves columns from one, then a subquery might be the way to go.