join query code example

Example 1: how to join tables in sql

JOINING 2 Tables in sql

SELECT X.Column_Name , Y.Column_Name2
FROM TABLES1_NAME X 
INNER JOIN TABLES2_NAME Y ON X.Primary_key = Y.Foreign_key;


--FOR EXAMPLE
--GET THE FIRST_NAME AND JOB_TITLE
--USE EMPLOYEES AND JOBS TABLE
--THE RELATIONSHIP IS JOB_ID

SELECT E.FIRST_NAME , J.JOB_TITLE
FROM EMPLOYEES E
INNER JOIN JOBS J ON J.JOB_ID = E.JOB_ID;

Example 2: join multiple tables sql

SELECT TableA.*, TableB.*, TableC.*, TableD.*
FROM TableA
    JOIN TableB
        ON TableB.aID = TableA.aID
    JOIN TableC
        ON TableC.cID = TableB.cID
    JOIN TableD
        ON TableD.dID = TableA.dID
WHERE DATE(TableC.date)=date(now())

Example 3: mysql left join

/*Two tables: CUSTOMERS table and ORDERS table.
ORDERS table contains STATUS attribute.*/
SELECT 
    customers.customerNumber, 
    customerName, 
    orderNumber, 
    status
FROM
    customers
LEFT JOIN orders ON 
    orders.customerNumber = customers.customerNumber;

Example 4: sql server joins

SELECT Orders.OrderID, Customers.CustomerName, Orders.OrderDate
FROM Orders
INNER JOIN Customers ON Orders.CustomerID=Customers.CustomerID;

Example 5: sql join on a subquery

SELECT * 
FROM
( SELECT ... FROM ... ) q1

INNER JOIN

( SELECT ... FROM ... ) q2

ON q1.colname = q2.colname

Example 6: join three tables sql

Suppose we are having three table named as 
Student_details
Attendance_details
Batch_details
And we have to apply join these three tables for fetching records

Example query:
select column_names
from Student_detail as s join Attendance_details as a on
s.s_id = a.s_id join Batch_details as b on 
s.s_id = b.s_id;

Here in the above example we implemented simple join but you change it with own join requirements.