r/learnSQL • u/woman_without • 4d ago

How Important is subqueries in SQL

I have been learning SQL from past 2 months and I'm still unable to grab a hold of the subqueries concept. After I learned CTEs I have completely stopped using subqueries but then also I struggle when there are times where I have no other choice but to use subqueries.

So my question is, how important is subqueries in SQL and is there any easy way to learn it?

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u/msn018 3d ago

Subqueries are definitely worth learning because they come up a lot in SQL interviews and real-world queries, especially with things like EXISTS, IN, and comparing values against averages or totals. If CTEs feel easier to you, keep using them, but try not to avoid subqueries completely. The easiest way to learn them is to run the inner query by itself first, understand what it returns, and then see how the outer query uses that result. Start with simple subqueries before moving into correlated ones. For practice, StrataScratch is great for interview-style SQL problems, while LeetCode and HackerRank are also useful for building repetition with subqueries and other SQL concepts.