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Master SQL with Adaptive AI.

Master SQL across 33 topics - Foundations, Joins and Aggregations, and Advanced SQL - guided by Leyaa's adaptive intelligence.

3Parts
33Topics
263Patterns
65hEst. duration
Start Learning Free
SQL
SQL Course
3 - part learning journey
Beginner
Foundations
12 topics · 93 patterns
Beginner
Intermediate
Joins and Aggregations
10 topics · 80 patterns
Intermediate
Advanced
Advanced SQL
11 topics · 90 patterns
Advanced
Begin Part 1: Foundations
✦ Course Structure

Your SQL Journey in 3 Parts

Each part builds on the last - a deliberate progression from beginner to advanced.

Beginner
Beginner
Part 1: Foundations
Covers Database Fundamentals, Creating and Managing Tables, Inserting Data and 9 more topics.
12Topics
93Patterns
View topics
Intermediate
Intermediate
Part 2: Joins and Aggregations
Covers Aggregate Functions, GROUP BY and HAVING, INNER JOIN and 7 more topics.
10Topics
80Patterns
View topics
Advanced
Advanced
Part 3: Advanced SQL
Covers Window Functions Fundamentals, Advanced Window Functions, Common Table Expressions (CTEs) and 8 more topics.
11Topics
90Patterns
View topics
Curriculum

Everything You'll Learn

Explore every topic and pattern in the course.

SQL

3 parts · 33 topics · 263 patterns
Beginner
Part 1: Foundations12 topics · 93 patterns
Beginner
01
Database Fundamentals
8 patterns
What is a database
Why databases over files
What is SQL
How SQL communicates with the database engine
Relational model mental model
Tables, rows, and columns concept
Primary keys and uniqueness
SQL statement categories (DDL, DML, DQL, DCL)
02
Creating and Managing Tables
9 patterns
Why table design matters
CREATE TABLE syntax
Column data types (INT, VARCHAR, DATE, DECIMAL)
NOT NULL constraint behavior
DEFAULT values
PRIMARY KEY constraint
AUTO_INCREMENT behavior
DROP TABLE and ALTER TABLE
TRUNCATE vs DELETE vs DROP
03
Inserting Data
7 patterns
Why INSERT matters
INSERT INTO single row
INSERT INTO multiple rows
INSERT with specific columns
INSERT with DEFAULT values
INSERT and auto-generated keys
Common INSERT errors and fixes
04
SELECT and Data Retrieval
7 patterns
Why SELECT is the most important command
SELECT all columns
SELECT specific columns
Column aliases with AS
DISTINCT for unique values
How the database engine processes a SELECT
SELECT with expressions and calculations
05
WHERE Clause and Filtering
10 patterns
Why filtering is essential
WHERE with comparison operators
WHERE with AND operator
WHERE with OR operator
WHERE with NOT operator
WHERE with BETWEEN range
WHERE with IN list
WHERE with LIKE pattern matching
WHERE with IS NULL and IS NOT NULL
Operator precedence in WHERE
06
NULL Semantics and Three-Valued Logic
9 patterns
Why NULL is not a value
Three-valued logic (TRUE, FALSE, UNKNOWN)
NULL behavior in comparisons
Why equals NULL fails
IS NULL vs equals NULL
NULL in AND, OR, NOT logic
NULL behavior in aggregate functions
NULLs in JOIN conditions
NULL in DISTINCT, GROUP BY, and ORDER BY
07
Sorting and Limiting Results
8 patterns
Why ordering matters
ORDER BY single column
ORDER BY multiple columns
ORDER BY with ASC and DESC
LIMIT clause behavior
OFFSET for pagination
ORDER BY with NULL values behavior
TOP vs LIMIT across databases
08
Updating Data
7 patterns
Why UPDATE needs caution
UPDATE single column
UPDATE multiple columns
UPDATE with WHERE condition
UPDATE without WHERE (danger)
UPDATE with expressions
UPDATE with subquery preview
09
Deleting Data
6 patterns
Why DELETE needs caution
DELETE with WHERE condition
DELETE without WHERE (danger)
DELETE vs TRUNCATE behavior
Soft delete pattern concept
CASCADE delete preview
10
String Functions
8 patterns
Why string functions matter in queries
UPPER and LOWER functions
LENGTH and CHAR_LENGTH
CONCAT and CONCAT_WS
SUBSTRING extraction
TRIM, LTRIM, RTRIM
REPLACE function
COALESCE for NULL handling
11
Numeric and Date Functions
8 patterns
Why built-in functions matter
ROUND, CEIL, FLOOR
ABS and MOD functions
CURRENT_DATE and CURRENT_TIMESTAMP
DATE_FORMAT and EXTRACT
DATE arithmetic (DATEDIFF, DATE_ADD)
YEAR, MONTH, DAY extraction
CAST and CONVERT for type changes
12
SQL Dialect Differences
6 patterns
Why dialect awareness matters
MySQL vs PostgreSQL vs SQL Server overview
LIMIT vs TOP vs FETCH FIRST syntax
String quoting and concatenation differences
AUTO_INCREMENT vs SERIAL vs IDENTITY
FULL OUTER JOIN availability across databases
Intermediate
Part 2: Joins and Aggregations10 topics · 80 patterns
Intermediate
01
Aggregate Functions
8 patterns
Why aggregation is needed
COUNT function behavior
COUNT(*) vs COUNT(column) difference
SUM function
AVG function
MIN and MAX functions
Aggregate with NULL handling
Combining multiple aggregates
02
GROUP BY and HAVING
9 patterns
Why grouping is needed
GROUP BY single column
GROUP BY multiple columns
How GROUP BY changes query execution
HAVING clause for filtering groups
WHERE vs HAVING mental model
GROUP BY with aggregate functions
GROUP BY with ORDER BY
GROUP BY with NULL values behavior
03
INNER JOIN
8 patterns
Why joins are needed
How the join engine matches rows
INNER JOIN syntax
INNER JOIN with ON condition
Joining on primary key to foreign key
INNER JOIN with multiple conditions
INNER JOIN with table aliases
Self join concept
04
LEFT and RIGHT JOIN
8 patterns
Why outer joins are needed
LEFT JOIN execution behavior
LEFT JOIN preserving all left rows
RIGHT JOIN execution behavior
LEFT JOIN with NULL result rows
Finding unmatched rows with LEFT JOIN
LEFT JOIN vs RIGHT JOIN decision
Multiple LEFT JOINs in one query
05
Advanced Joins
8 patterns
Why advanced joins matter
FULL OUTER JOIN behavior
CROSS JOIN cartesian product
Self join for hierarchical data
Joining more than two tables
Join order and performance impact
Natural join and its risks
Non-equi joins
06
Subqueries
9 patterns
Why subqueries are needed
Scalar subquery in SELECT
Subquery in WHERE clause
Subquery with IN operator
Subquery with EXISTS operator
Correlated subquery execution model
Subquery in FROM clause (derived table)
Subquery vs JOIN performance trade-off
Nested subqueries
07
Set Operations
7 patterns
Why set operations are needed
UNION combining result sets
UNION ALL with duplicates
INTERSECT for common rows
EXCEPT (MINUS) for differences
Set operation column matching rules
Set operations with ORDER BY
08
Table Constraints
9 patterns
Why constraints matter
NOT NULL constraint
UNIQUE constraint
CHECK constraint
FOREIGN KEY constraint
Foreign key ON DELETE behavior
Foreign key ON UPDATE behavior
Composite primary keys
Constraint naming conventions
09
Table Relationships
7 patterns
Why understanding relationships matters
One-to-one relationship design
One-to-many relationship design
Many-to-many with junction tables
Foreign key linking mental model
Referential integrity enforcement
ER diagram to table mapping
10
Views
7 patterns
Why views are needed
CREATE VIEW syntax
Querying through views
View as a saved query mental model
Updatable views and limitations
Dropping and altering views
Views for security and abstraction
Advanced
Part 3: Advanced SQL11 topics · 90 patterns
Advanced
01
Window Functions Fundamentals
8 patterns
Why window functions are needed
Window function vs GROUP BY mental model
ROW_NUMBER function
RANK and DENSE_RANK difference
NTILE for distribution
OVER clause with PARTITION BY
OVER clause with ORDER BY
Window frame specification (ROWS BETWEEN)
02
Advanced Window Functions
8 patterns
Why advanced window functions matter
LAG function for previous row access
LEAD function for next row access
FIRST_VALUE and LAST_VALUE
NTH_VALUE function
Running totals with SUM OVER
Moving averages with window frames
Percent of total with window functions
03
Common Table Expressions (CTEs)
9 patterns
Why CTEs are needed
WITH clause syntax
CTE as readable subquery replacement
Multiple CTEs in one query
CTE referencing another CTE
Recursive CTE concept
Recursive CTE for hierarchical data
Recursive CTE for series generation
CTE vs subquery vs view decision
04
CASE Expressions
9 patterns
Why CASE expressions are needed
Simple CASE syntax
Searched CASE syntax
CASE in SELECT for computed columns
CASE in WHERE clause
CASE in ORDER BY
CASE with aggregate functions
Nested CASE expressions
COALESCE and NULLIF as CASE shortcuts
05
Transactions and Data Integrity
9 patterns
Why transactions are needed
ACID properties mental model
BEGIN TRANSACTION syntax
COMMIT and ROLLBACK behavior
Savepoints within transactions
Transaction isolation levels
Read phenomena (dirty reads, phantom reads)
Deadlock concept and prevention
Auto-commit behavior
06
Indexes and Query Performance
10 patterns
Why indexes matter
How an index works (B-tree mental model)
CREATE INDEX syntax
Single column index
Composite index and column order
Unique index behavior
When indexes help and when they hurt
Index impact on INSERT and UPDATE
Covering index concept
EXPLAIN plan for query analysis
07
Stored Procedures and Functions
9 patterns
Why stored procedures are needed
CREATE PROCEDURE syntax
Parameters (IN, OUT, INOUT)
Variables and SET statements
IF-ELSE in procedures
WHILE loops in procedures
CURSOR concept and usage
User-defined functions
Function vs procedure decision
08
Triggers
8 patterns
Why triggers are needed
BEFORE trigger execution
AFTER trigger execution
INSERT trigger
UPDATE trigger with OLD and NEW
DELETE trigger
Trigger for audit logging
Trigger performance considerations
09
Database Design and Normalization
7 patterns
Why normalization matters
First Normal Form (1NF)
Second Normal Form (2NF)
Third Normal Form (3NF)
Denormalization and when to use it
Star schema concept
Database design best practices
10
Advanced Query Patterns
8 patterns
Why query patterns matter
Pivot and unpivot concepts
Running total without window functions
Finding gaps in sequences
Finding duplicates efficiently
Top-N per group query
Date range overlap detection
Conditional aggregation pattern
11
SQL Security Basics
5 patterns
Why SQL security awareness matters
How SQL injection exploits queries
How string concatenation creates vulnerabilities
Why prepared statements exist
Parameter binding mental model
Why Leyaa

Not just a course. A learning intelligence.

Leyaa doesn't just deliver content - it understands where you are, what you need, and how to get you there fastest.

Adaptive Diagnostics
Adaptive Diagnostics
Leyaa identifies which of the 263 patterns you've mastered and which need work - before you waste time on what you already know.
Pattern-Level Precision
Pattern-Level Precision
Every pattern gets a verdict - Learn, Practice, or Skip - so your study time goes exactly where it counts.
Intelligent Pacing
Intelligent Pacing
Leyaa reads your velocity across the whole course and adapts your focus list dynamically, keeping you in the optimal learning zone.
Before & After Visibility
Before & After Visibility
Every assessment creates a snapshot. Retake anytime to see exactly how much you've grown - topic by topic, pattern by pattern.
Learner Autonomy
Learner Autonomy
Leyaa recommends, never restricts. Override any suggestion and explore at your own pace - the system tracks everything regardless.
Clear Learning Path
Clear Learning Path
Foundations → Joins and Aggregations → Advanced SQL - a structured journey where each part sets you up perfectly for the next.
SQL

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33 Topics
263 Patterns
Personalized roadmap
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