MySQL CROSS JOIN

MySQL CROSS JOIN


A CROSS JOIN in MySQL produces the Cartesian product of two tables.

  • It combines every row from the first table with every row from the second table.
  • If the first table has m rows and the second table has n rows, the result will have m × n rows.
  • Unlike other joins, CROSS JOIN does not require a join condition using ON.


CROSS JOIN Syntax


SELECT table1.column_name, table2.column_name
FROM table1
CROSS JOIN table2;


Example Scenario:


Consider two tables:


Students Table:

student_id

name 

gender

city

age

score

course_id

email

phone_number

1

Alice

Female

Delhi

20

85

101

NULL

1234567890

2

Bob

Male

Mumbai

22

75

NULL

bob@email.com

NULL

3

Charlie

Male

Delhi

21

95

102

NULL

NULL

4

David

Male

Bangalore

23

65

101

david@email.com

NULL

5

Eve

Female

Mumbai

20

80

103

NULL

NULL

6

Frank

Male

Delhi

22

90

103

NULL

NULL

7

Alice

Female

Mumbai

19

60

102

NULL

NULL

Courses Table:

course_name

course_name

101

Math

102

Science

103

History

104

English

The following SQL statement selects all students, and all courses:

Example
SELECT students.name, courses.course_name
FROM students
CROSS JOIN courses;

Try it yourself

Explanation:

  • The CROSS JOIN keyword returns all matching records from both tables whether the other table matches or not. So, if there are rows in "Students" that do not have matches in "Courses", or if there are rows in "Courses" that do not have matches in "Students", those rows will be listed as well.

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