SQL Keywords Reference

This reference provides a comprehensive list of common SQL keywords and their functionalities. Note that the specific syntax and availability of certain keywords might vary slightly depending on the database system (e.g., MySQL, PostgreSQL, SQL Server, Oracle) you are using. Always refer to your database's documentation for the most accurate and up-to-date information.

Data Definition Language (DDL) Keywords

Keyword Description
ADD Adds a column to an existing table.
ADD CONSTRAINT Adds a constraint to a table.
ALTER Modifies the structure of a table (adding, deleting, or changing columns).
ALTER COLUMN Changes the data type of a column.
ALTER TABLE Modifies the structure of a table.
CHECK Defines a constraint to limit values in a column.
COLUMN Used within ALTER TABLE to specify a column.
CONSTRAINT Used to define or drop constraints.
CREATE Creates database objects (databases, tables, indexes, views, etc.).
CREATE DATABASE Creates a new database.
CREATE INDEX Creates an index on a table (allows duplicates).
CREATE OR REPLACE VIEW Creates or updates a view.
CREATE PROCEDURE Creates a stored procedure.
CREATE TABLE Creates a new table.
CREATE UNIQUE INDEX Creates a unique index on a table (no duplicates).
CREATE VIEW Creates a view.
DATABASE Used in CREATE or DROP statements for databases.
DEFAULT Specifies a default value for a column.
DROP Deletes database objects (databases, tables, indexes, views, etc.).
DROP COLUMN Deletes a column from a table.
DROP CONSTRAINT Deletes a constraint from a table.
DROP DATABASE Deletes a database.
DROP DEFAULT Removes a default value constraint from a column.
DROP INDEX Deletes an index from a table.
DROP TABLE Deletes a table.
DROP VIEW Deletes a view.
FOREIGN KEY Defines a foreign key constraint.
INDEX Used in CREATE or DROP statements for indexes.
PRIMARY KEY Defines a primary key constraint.
PROCEDURE Used in CREATE or DROP statements for stored procedures.
TABLE Used in CREATE, ALTER, or DROP statements for tables.
UNIQUE Defines a uniqueness constraint.
VIEW Used in CREATE or DROP statements for views.

Data Manipulation Language (DML) Keywords

Keyword Description
DELETE Deletes rows from a table.
INSERT INTO Inserts new rows into a table.
INSERT INTO SELECT Inserts data from one table into another.
SELECT Retrieves data from a database.
SELECT DISTINCT Retrieves unique rows only.
SELECT INTO Creates a new table and populates it with data from a query.
SELECT TOP Retrieves a limited number of rows.
SET Specifies values to update in an UPDATE statement.
TRUNCATE TABLE Deletes all data from a table but preserves its structure.
UPDATE Modifies existing rows in a table.
VALUES Specifies values for inserting new rows.

Data Control Language (DCL) Keywords

Keyword Description
GRANT Grants database permissions.
REVOKE Revokes database permissions.

Other Important Keywords

Keyword Description
ALL Used with subqueries; checks if all values meet a condition.
AND A logical operator; combines conditions; both must be true.
ANY Used with subqueries; checks if any value meets a condition.
AS Creates an alias for a column or table.
ASC Sorts in ascending order.
BETWEEN Selects values within a range.
CASE Performs conditional logic.
DESC Sorts in descending order.
DISTINCT Returns only unique rows.
DROP Used to delete database objects.
EXISTS Checks for the existence of rows.
FROM Specifies the table to select data from.
FULL OUTER JOIN Combines rows from two tables, including all rows from both.
GROUP BY Groups rows with the same values into summary rows.
HAVING Filters grouped rows based on aggregate functions.
IN Specifies multiple values in a WHERE clause.
INNER JOIN Returns only rows with matches in both joined tables.
IS NULL Checks for null values.
IS NOT NULL Checks for non-null values.
JOIN A general term for combining data from multiple tables.
LEFT JOIN Returns all rows from the left table and matched rows from the right.
LIKE Used for pattern matching in strings.
LIMIT Limits the number of rows returned.
NOT Negates a condition.
NOT NULL Enforces that a column cannot contain NULL values.
OR A logical operator; combines conditions; at least one must be true.
ORDER BY Sorts the result set.
OUTER JOIN A general term for joins that include all rows from at least one table.
RIGHT JOIN Returns all rows from the right table and matched rows from the left.
ROWNUM Used in Oracle to limit the number of rows returned.
UNION Combines result sets, removing duplicates.
UNION ALL Combines result sets, including duplicates.
WHERE Filters a result set based on specified conditions.