MySQL Tutorial

This SQL tutorial is structured for beginners to guide them from the foundational concepts to advanced data manipulation and querying techniques in SQL. By the end of this tutorial, you will have developed a robust understanding of SQL, equipping you with the knowledge to efficiently manage and analyze data across various database systems. This guide sets the stage for your growth into a skilled data professional, ready to tackle complex data challenges and contribute to the field of data analysis and database management.

 Cross Join
MySQL Cross Join
A MySQL Cross Join combines each row of the first table with each row of second table. It is a basic type of inner join that is used to retrieve the Cartesian product (or cross product) of two individual tables (i.e. permutations).
A Cartesian product, or a cross product, is the result achieved from multiplication of two sets. This is done by multiplying all the possible pairs from both the sets.
The sample figure below illustrates the cross join in a simple manner.
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Syntax
Following is the basic syntax of the Cross Join query in MySQL −
SELECT column_name(s)
FROM table1
CROSS JOIN table2
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Example
In this example of cross join, let us first create a table named CUSTOMERS, which contains personal details of customers including their name, age, address and salary etc.
CREATE TABLE CUSTOMERS (
   ID INT NOT NULL,
   NAME VARCHAR (20) NOT NULL,
   AGE INT NOT NULL,
   ADDRESS CHAR (25),
   SALARY DECIMAL (18, 2),       
   PRIMARY KEY (ID)
);
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Now insert values into this table using the INSERT statement as follows −
INSERT INTO CUSTOMERS VALUES
(1, 'Ramesh', 32, 'Ahmedabad', 2000.00 ),
(2, 'Khilan', 25, 'Delhi', 1500.00 );
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The table will be created as −
ID
NAME
AGE
ADDRESS
SALARY
1
Ramesh
32
Ahmedabad
2000.00
2
Khilan
25
Delhi
1500.00
Let us create another table ORDERS, containing the details of orders made and the date they are made on.
CREATE TABLE ORDERS (
   OID INT NOT NULL,
   DATE VARCHAR (20) NOT NULL,
   CUSTOMER_ID INT NOT NULL,
   AMOUNT DECIMAL (18, 2),
);
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Using the INSERT statement, insert values into this table as follows −
INSERT INTO ORDERS VALUES 
(100, '2009-10-08 00:00:00', 3, 1500.00),
(101, '2009-11-20 00:00:00', 2, 1560.00);
﻿
The table is displayed as follows −
OID
DATE
CUSTOMER_ID
AMOUNT
100
2009-10-08 00:00:00
3
1500.00
101
2009-11-20 00:00:00
2
1560.00
Now, if we execute the following Cross Join query on these two tables given above, the cross join combines each row in CUSTOMERS table with each row in ORDERS table.
SELECT ID, NAME, AMOUNT, DATE
FROM CUSTOMERS
CROSS JOIN ORDERS;
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Output
The resultant table is as follows −
ID
NAME
AMOUNT
DATE
2
Khilan
1500.00
2009-10-08 00:00:00
1
Ramesh
1560
2009-11-20 00:00:00
2
Khilan
1560
2009-11-20 00:00:00
1
Ramesh
1500.00
2009-10-08 00:00:00
Joining Multiple Tables with Cross Join
We can also join more than two tables using cross join. In this case, multiple-way permutations are displayed and the resultant table is expected to contain way more records than the individual tables.
Syntax
Following is the syntax to join multiple tables using cross join in MySQL −
SELECT column_name(s)
FROM table1
CROSS JOIN table2
CROSS JOIN table3
CROSS JOIN table4
.
.
.
﻿
Example
Let us now combine three tables CUSTOMERS, ORDERS and ORDER_RANGE, to demonstrate combining multiple tables using cross join.
We will create the ORDER_RANGE table using the query below −
CREATE TABLE ORDER_RANGE (
   SNO INT NOT NULL,
   ORDER_RANGE VARCHAR (20) NOT NULL,
);
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Now, we can insert values into this empty tables using the INSERT statement as follows −
INSERT INTO ORDER_RANGE VALUES
(1, '1-100'),
(2, '100-200'),
(3, '200-300');
﻿
The ORDER_RANGE table is as follows −
SNO
ORDER_RANGE
1
1-100
2
100-200
3
200-300
Now we use the following cross join query on the given tables,
SELECT ID, NAME, AMOUNT, DATE, ORDER_RANGE
FROM CUSTOMERS
CROSS JOIN ORDERS
CROSS JOIN ORDER_RANGE;
﻿
Output
The resultant table is given below −
ID
NAME
AMOUNT
DATE
ORDER_RANGE
2
Khilan
1560
2009-11-20 00:00:00
1-100
1
Ramesh
1560
2009-11-20 00:00:00
1-100
2
Khilan
1500.00
2009-10-08 00:00:00
1-100
1
Ramesh
1500.00
2009-10-08 00:00:00
1-100
2
Khilan
1560
2009-11-20 00:00:00
100-200
1
Ramesh
1560
2009-11-20 00:00:00
100-200
2
Khilan
1500.00
2009-10-08 00:00:00
100-200
1
Ramesh
1500.00
2009-10-08 00:00:00
100-200
2
Khilan
1560
2009-11-20 00:00:00
200-300
1
Ramesh
1560
2009-11-20 00:00:00
200-300
2
Khilan
1500.00
2009-10-08 00:00:00
200-300
1
Ramesh
1500.00
2009-10-08 00:00:00
200-300
Cross Join Using Client Program
We can also perform the Cross join operation on one or more tables using a client program.
Syntax
PHPNodeJSJavaPython
To perform cross Join through a PHP program, we need to execute the SQL query with CROSS JOIN clause using the mysqli function query() as follows −
$sql = "SELECT a.tutorial_id, a.tutorial_author, b.tutorial_count FROM tutorials_tbl a CROSS JOIN tcount_tbl b";
$mysqli->query($sql);
﻿
Example
Following are the programs −
PHPNodeJSJavaPython
$dbhost = 'localhost';
$dbuser = 'root';
$dbpass = 'password';
$dbname = 'TUTORIALS';
$mysqli = new mysqli($dbhost, $dbuser, $dbpass, $dbname);
if ($mysqli->connect_errno) {
    printf("Connect failed: %s", $mysqli->connect_error);
    exit();
}
// printf('Connected successfully.');
﻿
$sql = 'SELECT a.tutorial_id, a.tutorial_author, b.tutorial_count
    FROM tutorials_tbl a CROSS JOIN tcount_tbl b';
$result = $mysqli->query($sql);
if ($result->num_rows > 0) {
    echo " following is the details after executing cross join! \n";
    while ($row = $result->fetch_assoc()) {
        printf("Id: %s, Author: %s, Count: %d", $row["tutorial_id"], $row["tutorial_author"], $row["tutorial_count"]);
        printf("\n");
    }
} else {
    printf('No record found.');
}
mysqli_free_result($result);
$mysqli->close();
﻿
Output
The output obtained is as follows −
following is the details after executing cross join!
Id: 102, Author: Sarika Singh, Count: 20
Id: 101, Author: Aman kumar, Count: 20
Id: 3, Author: Sanjay, Count: 20
Id: 2, Author: Abdul S, Count: 20
Id: 1, Author: John Poul, Count: 20
Id: 102, Author: Sarika Singh, Count: 5
Id: 101, Author: Aman kumar, Count: 5
Id: 3, Author: Sanjay, Count: 5
Id: 2, Author: Abdul S, Count: 5
Id: 1, Author: John Poul, Count: 5
Id: 102, Author: Sarika Singh, Count: 4
Id: 101, Author: Aman kumar, Count: 4
Id: 3, Author: Sanjay, Count: 4
Id: 2, Author: Abdul S, Count: 4
Id: 1, Author: John Poul, Count: 4
Id: 102, Author: Sarika Singh, Count: 20
Id: 101, Author: Aman kumar, Count: 20
Id: 3, Author: Sanjay, Count: 20
Id: 2, Author: Abdul S, Count: 20
Id: 1, Author: John Poul, Count: 20
Id: 102, Author: Sarika Singh, Count: 1
Id: 101, Author: Aman kumar, Count: 1
Id: 3, Author: Sanjay, Count: 1
Id: 2, Author: Abdul S, Count: 1
Id: 1, Author: John Poul, Count: 1
Id: 102, Author: Sarika Singh, Count: 1
Id: 101, Author: Aman kumar, Count: 1
Id: 3, Author: Sanjay, Count: 1
Id: 2, Author: Abdul S, Count: 1
Id: 1, Author: John Poul, Count: 1   
﻿
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OID	DATE	CUSTOMER_ID	AMOUNT
100	2009-10-08 00:00:00	3	1500.00
101	2009-11-20 00:00:00	2	1560.00

ID	NAME	AMOUNT	DATE
2	Khilan	1500.00	2009-10-08 00:00:00
1	Ramesh	1560	2009-11-20 00:00:00
2	Khilan	1560	2009-11-20 00:00:00
1	Ramesh	1500.00	2009-10-08 00:00:00

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MySQL Tutorial

Cross Join

MySQL Cross Join

Syntax

Example

Output

Joining Multiple Tables with Cross Join

Syntax

Example

Output

Cross Join Using Client Program

Syntax

Example

Output