Master programming syntax, solve interactive challenges & run live code in Syntaxis Explore Arena →
menu_book Course Curriculum (SQLite Complete Course) expand_more
Core SQL
CREATE TABLE INSERT SELECT WHERE ORDER BY LIMIT UPDATE DELETE DISTINCT Aliases
Expressions & Filters
AND OR NOT IN BETWEEN LIKE GLOB IS NULL CASE expression COALESCE NULLIF CAST
Joins & Grouping
INNER JOIN LEFT JOIN CROSS JOIN Self join GROUP BY HAVING COUNT SUM AVG MIN MAX GROUP_CONCAT FILTER clause
Constraints & Schema
PRIMARY KEY INTEGER PRIMARY KEY rowid UNIQUE NOT NULL CHECK FOREIGN KEY Generated columns STRICT tables WITHOUT ROWID ALTER TABLE
Indexes & Query Planner
CREATE INDEX Composite index Partial index Expression index UNIQUE index EXPLAIN QUERY PLAN ANALYZE PRAGMA optimize Covering index concept Index selectivity
Transactions & Concurrency
BEGIN transaction COMMIT ROLLBACK SAVEPOINT ROLLBACK TO Deferred transaction Immediate transaction Exclusive transaction WAL mode Busy timeout
SQLite Functions
datetime() strftime() json_extract() json_each() printf() instr() substr() replace() random() changes()
Advanced SQLite
Common table expressions Recursive CTE Window ROW_NUMBER Window LAG UPSERT ON CONFLICT RETURNING clause ATTACH DATABASE VACUUM FTS5 virtual table Triggers
SQLite Complete Course / Constraints & Schema

UNIQUE

Learn UNIQUE in SQLite through the exact construct, a dedicated example, a boundary case, and a mastery check.

10 min read • Intermediate

UNIQUE is an atomic SQLite lesson inside Constraints & Schema. The example uses the specific syntax, command, API, instruction, or language rule named by this lesson.

Study the construct itself, then change one relevant input and predict the result before running it. That keeps this lesson focused on UNIQUE rather than on generic SQLite syntax.

Topic-specific example

sqlite-04-03.sql
sql Try It Live 
CREATE TABLE users (id INTEGER PRIMARY KEY, email TEXT UNIQUE);
Edge case / engineering note

Test UNIQUE with an empty result, NULL/missing value, duplicate key, or concurrent operation where relevant; database behavior should be verified at the boundary shown by this example.

Content source & attribution
Original Syntaxis Content · Original Syntaxis Content

Lesson quizzes

UNIQUE Mastery Check →
← PREVIOUS
INTEGER PRIMARY KEY rowid
NEXT →
NOT NULL