SQL Recall
104 lessons & exercises across 11 categories
5 lessons, 9 exercises
SQL Foundations
Execution order, SELECT, FROM, WHERE, BETWEEN, IN, LIKE, ORDER BY, LIMIT, DISTINCT, NULL
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3 lessons, 6 exercises
Aggregations
COUNT, SUM, AVG, MIN/MAX, GROUP BY, HAVING
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4 lessons, 6 exercises
Joins
INNER, LEFT, SELF, CROSS joins, anti-join patterns
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2 lessons, 4 exercises
CASE & Conditional Logic
CASE WHEN, COALESCE, NULLIF, conditional aggregation
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2 lessons, 5 exercises
Subqueries
Scalar subqueries, correlated subqueries, EXISTS vs IN
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3 lessons, 9 exercises
Common Table Expressions
WITH clause, multiple CTEs, recursive CTEs
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4 lessons, 8 exercises
Window Functions
ROW_NUMBER, RANK, LAG/LEAD, running totals, frames
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2 lessons, 5 exercises
Date & Time
Date arithmetic, strftime, date grouping, intervals
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2 lessons, 5 exercises
String & Set Operations
SUBSTR, REPLACE, LENGTH, UNION, INTERSECT, EXCEPT
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3 lessons, 5 exercises
Query Optimization
Indexes, EXPLAIN plans, sargable queries, anti-patterns, N+1 problem
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3 lessons, 9 exercises
Advanced Patterns
Top-N per group, pivoting, sessionization, funnels, cohort retention
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