This reading introduces why simple SELECT statements are insufficient for real-world database work and previews the complex SQL concepts—JOINs, filtering, aggregation, and subqueries—that learners will study throughout the module.
Topics
This module covers 6 topics. Open a topic to see its subtopics.
Module Content
14 items.
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This reading explains all major SQL JOIN types (INNER, LEFT, RIGHT, FULL, CROSS) and how to combine data from multiple related tables, serving as a reference and study resource for learners writing multi-table queries.
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This reading covers the SQL WHERE clause in depth—including comparison operators, logical operators (AND, OR, NOT), pattern matching with LIKE, IN, BETWEEN, and NULL handling—so learners can precisely filter query results to only the rows they need.
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This reading explains how the ORDER BY clause controls the sequence of query results, covering ascending and descending sorts, multi-column sort keys, and sorting by expressions, so learners can return data in a predictable, meaningful order.
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This reading covers the GROUP BY clause and aggregate functions (COUNT, SUM, AVG, MIN, MAX) along with the HAVING clause for filtering grouped results, enabling learners to write queries that produce summary statistics across categories of data.
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This reading introduces subqueries—SELECT statements nested inside other SQL statements—explaining how to write and place them in WHERE, FROM, and SELECT clauses so learners can decompose complex data retrieval problems into manageable logical steps.
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This reading is a duplicate of artifact 6 and covers the same subquery concepts—nested SELECT statements, inner/outer query terminology, and practical placement strategies—providing learners with the same reference material on writing and using subqueries.
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An orienting reading that defines what makes a SQL query 'complex' — multi-table joins, layered filtering, grouping, and nesting — and previews the business questions such queries answer, giving learners the conceptual framing before they tackle individual clause topics.
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A lesson on why relational data is split across tables and how INNER, LEFT, RIGHT, and FULL joins recombine it, which learners use to practice writing multi-table SELECT statements with correct join conditions.
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A reading on the WHERE clause covering comparison and logical operators, range and pattern matching (BETWEEN, IN, LIKE), and NULL handling, used by learners to restrict query results to exactly the rows they need.
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A focused explanation of ORDER BY — single and multi-column sorting, ascending versus descending, and its position as the last clause evaluated — that learners apply to control the presentation order of result sets.
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A lesson on collapsing rows into summary results with GROUP BY and aggregate functions (COUNT, SUM, AVG, MIN, MAX), plus using HAVING to filter groups, which learners use to produce reports and answer 'how many' or 'what average' questions.
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A reading on nesting SELECT statements inside other statements, explaining how inner queries return a single value, a list, or a derived table for the outer query, used by learners to replace multi-step manual lookups with one query.
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A consolidated single-page version of the entire module that strings together all five topic readings — complex query concepts, JOINs, WHERE, ORDER BY, GROUP BY/HAVING, and subqueries — convenient for review, printing, or offline study.