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