Understanding Subquery and Common Table Expressions(CTEs)
The article explains the concepts of subqueries and Common Table Expressions (CTEs) in SQL. It outlines the types of subqueries, including scalar and list subqueries, and discusses when to use them. Additionally, it compares subqueries with CTEs, highlighting their differences in structure and usability.
- ▪A subquery is a select statement within another select statement, where the inner query runs first.
- ▪Common Table Expressions (CTEs) are temporary result sets defined at the start of a query using the WITH keyword.
- ▪Subqueries are typically used for simple filtering, while CTEs are better suited for complex queries.
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| Original publisher | DEV Community |
| Canonical URL | https://dev.to/gabriel_njoroge_5be6652c3/understanding-subquery-and-common-table-expressionsctes-391j |
| Publication time | Tue, 28 Apr 2026 12:40:41 +0000 |
| Retrieval time | 2026-04-28T12:54:31.957Z |
| Last seen | 2026-04-28T12:54:31.957Z |
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| Commercial reuse | May the content be reused commercially? | Not permitted |
Basis: Derived from the published RSS/Atom feed. Contact: [email protected]. Reviewed: 2026-07-24.
Opening excerpt (first ~120 words) tap to expand
try { if(localStorage) { let currentUser = localStorage.getItem('current_user'); if (currentUser) { currentUser = JSON.parse(currentUser); if (currentUser.id === 3564637) { document.getElementById('article-show-container').classList.add('current-user-is-article-author'); } } } } catch (e) { console.error(e); } Gabriel Njoroge Posted on Apr 28 Understanding Subquery and Common Table Expressions(CTEs) #beginners #database #sql #tutorial What is a Subquery? A subquery is simply a select statement written inside another select statement. The inside query runs first and results is handed to outer query for use. Example: Explanation i)First it finds the Average Score ii)It finds all rows which are greater than the Average score. Types of Subqueries 1.
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Excerpt limited to ~120 words for fair-use compliance. The full article is at DEV Community.
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