SQL

67 topics · Stage 1

Complete

Basic17

01Basic NotesSQL basics: databases, tables, data types, comments, and the first commands.1 min
02SQL OperationsCommon SQL operations for creating, inspecting, changing, and querying data.2 min
03DCL and TransactionsPermissions and transaction control with GRANT, REVOKE, COMMIT, and ROLLBACK.2 min
04Introduction to DDLDDL commands for creating and changing database tables and their structure.2 min
05CHECK Constraints and Data ValidationUsing CHECK constraints to keep invalid values out of database tables.2 min
06NOT NULL, PRIMARY KEY, and NULL ValuesNOT NULL and PRIMARY KEY constraints, plus the difference between NULL, zero, and empty text.4 min
07UNIQUE, DEFAULT, and AUTO_INCREMENTUNIQUE and DEFAULT constraints with MySQL AUTO_INCREMENT behavior.3 min
08Foreign Keys and RelationshipsForeign keys, referential integrity, and relationships between SQL tables.7 min
09Basic SQL CommandsBasic SELECT queries, expressions, DISTINCT, sorting, and limiting results.7 min
10SELECT and FROMHow SELECT and FROM shape a query and its result set.6 min
11The WHERE ClauseA detailed look at filtering rows with SQL's WHERE clause.4 min
12Comparison OperatorsFiltering SQL rows with equality, inequality, and range comparisons.6 min
13Logical OperatorsCombining SQL conditions with AND, OR, NOT, and parentheses.6 min
14Arithmetic OperatorsCalculating values in SQL with arithmetic operators and expressions.5 min
15ORDER BY and LIMITSorting SQL results and returning a limited, deterministic set of rows.5 min
16DISTINCT and AliasesRemoving duplicate result rows and naming SQL expressions with aliases.5 min
17SQL Filtering EssentialsPractical SQL filtering with ranges, lists, patterns, and NULL checks.5 min

Advanced27

01SQL Query LifecycleWhat happens between sending a SQL query and receiving its result.6 min
02SQL IndexingHow indexes speed up reads, when they help, and what they cost.6 min
03Filtering Essentials in DetailA deeper pass through BETWEEN, IN, LIKE, NULL, and negated filters.6 min
04Aggregation and Data SummarisationSummarising SQL data with aggregate functions, GROUP BY, and HAVING.9 min
05Common Aggregation MistakesCommon GROUP BY, HAVING, NULL, and aggregate-function mistakes to avoid.4 min
06SQL Utility FunctionsUseful numeric and NULL-handling functions for everyday SQL queries.8 min
07CASE ExpressionsUsing CASE expressions for conditional values, labels, and calculations.19 min
08String FunctionsCommon MySQL string functions for cleaning, matching, and formatting text.17 min
09Editing Data and TablesEdit table data and structure with INSERT, UPDATE, DELETE, ALTER, and TRUNCATE.23 min
10Merging Query ResultsCombine compatible query results with UNION, UNION ALL, and safe intersection patterns.12 min
11Joins Deep DiveUnderstand inner, outer, cross, self, implicit, and natural joins in depth.23 min
12Access ControlManage MySQL users, roles, privileges, grants, revocation, and account access safely.18 min
13Connections and TransactionsUnderstand MySQL connections, transaction control, isolation, locks, and failure handling.15 min
14Mastering SubqueriesUse scalar, row, table, correlated, and nested subqueries with clear execution models.18 min
15Common Table ExpressionsStructure complex queries with non-recursive and recursive common table expressions.19 min
16Working with DatesWork with MySQL dates, timestamps, intervals, extraction, formatting, and comparisons.21 min
17Window FunctionsCalculate rankings, running values, offsets, distributions, and partitions with window functions.58 min
18JSON in SQLStore, query, validate, update, aggregate, index, and upsert JSON data in MySQL.49 min
19Database Design FundamentalsDesign relational schemas with entities, relationships, keys, constraints, and normalization.39 min
20Stored ProceduresCreate, secure, inspect, and execute reusable MySQL stored procedures safely.9 min
21Performance and DebuggingAnalyze MySQL plans, design useful indexes, write sargable predicates, and debug incorrect queries.23 min
22Storage, Keys, Query and PerformanceUnderstand InnoDB pages, clustered keys, buffer pools, redo logs, and B+ tree index costs.54 min
23Scaling, Production and OperationsScale MySQL with replicas, sharding, distributed IDs, online migrations, and data lifecycle practices.52 min
24Isolation Levels and LockingLearn the four read anomalies, the four isolation levels, MVCC, row locks, SKIP LOCKED queues, and optimistic vs pessimistic locking.23 min
25ViewsUse views to hide columns and simplify joins, learn updatable views and WITH CHECK OPTION, and compare views with materialized views.17 min
26TriggersWrite MySQL triggers with NEW and OLD for audit logs, validation, and counters, and learn why many teams avoid them and what to use instead.16 min
27PaginationCompare LIMIT/OFFSET with keyset (cursor) pagination: why deep pages get slow, how rows go missing, the index you need, and cheap total counts.18 min

Revision4

01Basic SQL MCQ RevisionMultiple-choice revision for basic SELECT, DISTINCT, ordering, and expressions.3 min
02SQL Filtering Essentials Quiz RevisionQuiz revision for WHERE, NULL, patterns, ranges, and logical conditions.4 min
03SQL Aggregation MCQsAggregation multiple-choice questions with answers and explanations.2 min
04String Functions QuizQuiz revision for MySQL string functions, matching, extraction, and character handling.8 min

Practice Problems19

01Basic Filtering ProblemsQuery-writing exercises for filtering rows with comparisons and conditions.13 min
02Filtering ProblemsQuery-writing exercises using SQL filtering conditions.15 min
03Aggregation ProblemsQuery-writing exercises using aggregates, GROUP BY, and HAVING.16 min
04Valid Triangle CheckWrite a CASE expression that checks whether three side lengths form a valid triangle.11 min
05Instant Food DeliveryCalculate the percentage of immediate orders with conditional aggregation.11 min
06Special Bonus CalculationCalculate employee bonuses with CASE, parity checks, and name filters.12 min
07Node ClassificationClassify tree nodes as root, inner, or leaf with SQL conditions and a subquery.14 min
08Apples vs OrangesFind the daily difference between apple and orange sales with conditional aggregation.12 min
09Query Quality AnalysisCalculate grouped query quality and poor-query percentages from rating data.14 min
10Number of Calls Between Two PersonsCombine calls in both directions and report their count and total duration.5 min
11Exceeding Tweet LengthFind tweets that exceed a character limit with a direct string-length filter.10 min
12Editing Data and Tables ProblemsPractice safe data and table changes with INSERT, UPDATE, DELETE, and ALTER.18 min
13Merging Query Results ProblemsPractice combining, deduplicating, and reshaping query results from multiple sources.36 min
14Joins Deep Dive ProblemsPractice inner, outer, cross, self, implicit, and natural join patterns.52 min
15Joins Level 2 ProblemsSolve multi-step join problems involving aggregation, ranges, self joins, and arithmetic.57 min
16Subquery ProblemsPractice scalar, correlated, aggregate, and relational-division subquery patterns.25 min
17Common Table Expression ProblemsPractice reusable and recursive common table expressions on realistic problems.22 min
18Date ProblemsPractice date filtering, comparison, aggregation, and anti-join patterns.25 min
19Return Child Rows as a JSON Array for Every ParentGroup child identifiers by parent and return each group as a MySQL JSON array.1 min