SQL Keywords

This lesson lists and explains all standard SQL keywords, including those not supported in our playground environment. Unsupported features are clearly marked so users know what to expect.

SQL Keywords Table Structure and Constraints

Keyword	Description	Playground Support Notes
ADD	Adds a column to an existing table	✅ Supported
ADD CONSTRAINT	Adds a constraint to an existing table	⚠️ Partially supported (some constraint types may not work)
ALTER	Modifies table structure (columns, types)	✅ Supported
ALTER COLUMN	Changes a column’s data type or properties	✅ Supported
ALTER TABLE	Adds, deletes, or modifies columns	✅ Supported
CHECK	Limits the value range of a column	⚠️ Not enforced in some playgrounds
COLUMN	Used with ALTER TABLE to reference a column	✅ Supported
CONSTRAINT	Used to define a rule for a column or table	⚠️ Not all constraint types supported
DEFAULT	Sets a default value for a column	⚠️ Supported in CREATE TABLE, but behavior may vary
DROP COLUMN	Deletes a column from a table	✅ Supported
DROP CONSTRAINT	Removes constraints like PRIMARY KEY, UNIQUE, etc.	⚠️ Limited support
NOT NULL	Ensures a column cannot have NULL values	✅ Supported
PRIMARY KEY	Uniquely identifies records in a table	✅ Supported
FOREIGN KEY	Links a column to another table’s key	⚠️ Not enforced in all playgrounds
UNIQUE	Ensures all values in a column are different	✅ Supported

SQL Keywords Data Definition (DDL)

Keyword	Description	Playground Support Notes
CREATE	Creates tables, views, indexes, etc.	✅ Supported
CREATE DATABASE	Creates a new database	❌ Not supported in our playground
CREATE INDEX	Adds an index to improve query speed	✅ Supported
CREATE OR REPLACE VIEW	Updates or replaces a view	❌ Not supported
CREATE PROCEDURE	Defines a stored procedure	❌ Not supported
CREATE TABLE	Creates a new table	✅ Supported
CREATE UNIQUE INDEX	Creates an index that ensures unique values	✅ Supported
CREATE VIEW	Defines a virtual table	✅ Supported
DATABASE	Refers to the current or another database	❌ Not supported in playground (single DB only)
DROP	Deletes tables, views, databases, etc.	✅ Supported
DROP DATABASE	Deletes an entire database	❌ Not supported
DROP DEFAULT	Removes a default constraint	⚠️ Might not apply depending on syntax support
DROP INDEX	Deletes an index	✅ Supported
DROP TABLE	Deletes a table	✅ Supported
DROP VIEW	Deletes a view	✅ Supported
EXEC	Executes a stored procedure	❌ Not supported
PROCEDURE	Refers to stored procedures	❌ Not supported
TABLE	Refers to a table for DDL or DML commands	✅ Supported
TRUNCATE TABLE	Deletes all rows, keeps structure	❌ Not supported in our playground

SQL Keywords Data Manipulation (DML)

Keyword	Description	Playground Support Notes
INSERT INTO	Adds new rows to a table	✅ Supported
INSERT INTO SELECT	Copies rows from one table to another	✅ Supported
UPDATE	Modifies existing records	✅ Supported
SET	Assigns values in an UPDATE	✅ Supported
DELETE	Removes rows from a table	✅ Supported
VALUES	Provides values for an INSERT	✅ Supported

SQL Keywords Query and Filtering

Keyword	Description	Playground Support Notes
SELECT	Retrieves data from one or more tables	✅ Supported
SELECT DISTINCT	Returns unique values only	✅ Supported
SELECT INTO	Creates a new table from a SELECT	✅ Supported
SELECT TOP	Limits rows returned (T-SQL)	❌ Use LIMIT instead
WHERE	Filters rows by condition	✅ Supported
AND	Combines conditions (both must be true)	✅ Supported
OR	Combines conditions (either can be true)	✅ Supported
NOT	Negates a condition	✅ Supported
IN	Checks if a value is in a list	✅ Supported
BETWEEN	Checks if a value is within a range	✅ Supported
LIKE	Searches for a pattern using wildcards	✅ Supported
IS NULL	Tests for NULL values	✅ Supported
IS NOT NULL	Tests for non-NULL values	✅ Supported
EXISTS	Tests for subquery existence	✅ Supported
CASE	Conditional logic in queries	✅ Supported
AS	Renames a column or table with an alias	✅ Supported

SQL Keywords Joins and Subqueries

Keyword	Description	Playground Support Notes
JOIN	Combines rows from two or more tables	✅ Supported
INNER JOIN	Returns matching rows in both tables	✅ Supported
LEFT JOIN	Returns all from left table + matched right	✅ Supported
RIGHT JOIN	Returns all from right table + matched left	✅ Supported
FULL OUTER JOIN	Returns all rows with matches in either table	❌ Not supported in our playground
OUTER JOIN	General outer join syntax	❌ Not supported
ANY	Returns true if any subquery values match	✅ Supported
ALL	Returns true if all subquery values match	✅ Supported

SQL Keywords Aggregates and Grouping

Keyword	Description	Playground Support Notes
GROUP BY	Groups rows for aggregate functions	✅ Supported
HAVING	Filters groups (used with aggregates)	✅ Supported
ORDER BY	Sorts result set by one or more columns	✅ Supported
ASC	Sorts in ascending order	✅ Supported
DESC	Sorts in descending order	✅ Supported

SQL Keywords Set Operations

Keyword	Description	Playground Support Notes
UNION	Combines SELECT results, no duplicates	✅ Supported
UNION ALL	Combines SELECT results, includes duplicates	✅ Supported

SQL Keywords Limits and Rows

Keyword	Description	Playground Support Notes
LIMIT	Limits the number of returned rows	✅ Supported
TOP	Limits rows (T-SQL style)	❌ Use LIMIT instead
ROWNUM	Oracle-style row limiting	❌ Not supported

SQL Keywords Labs