SQL Keywords

A list of the most important keywords in SQL

SELECT

Retrieve data from a table

FROM

Specify the table

WHERE

Filter records

GROUP BY

Group rows with the same values

HAVING

Filter groups

ORDER BY

Sort results

DISTINCT

Remove duplicates

LIMIT

Restrict number of rows returned

OFFSET

Skip rows (Pagination)

CREATE TABLE

Create a new table

ALTER TABLE

Modify an existing table

DROP TABLE

Delete a table

TRUNCATE

Remove all records from a table (not to be confused with trunc)

RENAME

Change the name of a table or column

COMMENT

Add comments to tables/columns

INSERT INTO

Add new records

UPDATE

Modify existing records

DELETE FROM

Remove records

GRANT

Give user permissions

REVOKE

Remove user permissions

INNER JOIN

Returns matching rows in both tables

LEFT JOIN

Returns all rows from the left table + matching rows from the right

RIGHT JOIN

Returns all rows from the right table + matching rows from the left

FULL JOIN

Returns all rows when there is a match in either table

CROSS JOIN

Returns a Cartesian product of both tables

PRIMARY KEY

Unique identifier for records

FOREIGN KEY

Links to another table’s primary key

UNIQUE

Ensures all values in a column are unique

NOT NULL

Ensures a column cannot have NULL values

AND

Both conditions must be true

OR

At least one condition must be true

NOT

Negates a condition

IN

Matches any value in a list

BETWEEN

Checks if a value is within a range

LIKE

Matches patterns using wildcards

IS NULL

Checks for NULL values

IS NOT NULL

Checks for values that are not NULL

USING()

Instead of using this

SELECT
 *
FROM table1
INNER JOIN table2 ON table1.id = table2.id;

• Keeps duplicate columns if selecting *

You can use

SELECT
 *
FROM table1
JOIN table2
USING (id);

• Only works if the column names are identical

• Automatically removes duplicate columns from the result, so the join column appears only once

Used with JOIN operations to simplify the ON condition when the columns you’re joining on have the same name in both tables.