How can you perform inner join on two tables using MySQL in Python?

PythonServer Side ProgrammingProgramming

We can join two tables in SQL based on a common column between them or based on some specified condition. There are different types of JOIN available to join two SQL tables.

Here, we will discuss about the inner join on two tables.

JOIN and INNER JOIN both work the same way. The INNER JOIN matches each row in one table with every row in other table and allows to combine the rows from both the tables which either have somecommon column or which satisfy some condition which is specified.

When applying join among two tables, we need to specify the condition based on which the tables will be joined.

Syntax

SELECT column1, column2...
FROM table_1
INNER JOIN table_2 ON condition;

Let there be two tables, “Students” and “Department” as folllows −

Students

+----------+--------------+-----------+
|    id    | Student_name |   Dept_id |
+----------+--------------+-----------+
|    1     |    Rahul    |    120     |
|    2     |    Rohit    |    121     |
|    3     |    Kirat    |    122     |
|    4     |    Inder    |    125     |
+----------+--------------+-----------+

Department

+----------+-----------------+
| Dept_id | Department_name  |
+----------+-----------------+
|    120   |    CSE          |
|    121   |    Mathematics  |
|    122   |    Physics      |
+----------+-----------------+

We will join the above tables based on the dept_id which is common in both the tables.

Steps to join two tables using MySQL in python

  • import MySQL connector

  • establish connection with the connector using connect()

  • create the cursor object using cursor() method

  • create a query using the appropriate mysql statements

  • execute the SQL query using execute() method

  • close the connection

Example

import mysql.connector
db=mysql.connector.connect(host="your host", user="your username", password="your
password",database="database_name")

cursor=db.cursor()

query="SELECT Students.Id,Students.Student_name,Department.Department_name
FROM Students INNER JOIN Department ON Students.Dept_Id=Department.Dept_Id"
cursor.execute(query)
rows=cursor.fetchall()
for x in rows:
   print(x)

db.close()

Output

(1, ‘Rahul’, ‘CSE’)
(2, ‘Rohit’, ‘Mathematics’)
(3, ‘Kirat’, ‘Physics’)

Notice, the 4th row is not included in the result because there is no mathcing record for the 4th row of Students table in the Department table.

raja
Published on 10-Jun-2021 12:46:52
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