SQL

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;

joins in sql

INNER JOIN:
is used when retrieving data from multiple
tables and will return only matching data.

LEFT OUTER JOIN:
is used when retrieving data from
multiple tables and will return
left table and any matching right table records.

RIGHT OUTER JOIN:
is used when retrieving data from
multiple tables and will return right
table and any matching left table records

FULL OUTER JOIN:
is used when retrieving data from
multiple tables and will return both
table records, matching and non-matching.



INNER JOIN :
SELECT select_list From TableA A
Inner Join TableB B
On A.Key = B.Key


LEFT OUTER JOIN :
SELECT select_list From TableA A
Left Join TableB B
On A.Key = B.Key

(where b.key is null)//For delete matching data



RIGTH OUTER JOIN :
SELECT select_list From TableA A
Right Join TableB B
On A.Key = B.Key


FULL JOIN :
SELECT select_list From TableA A
FULL OUTER Join TableB B
On A.Key = B.Key

Syntax for JOIN in SQL

SELECT table1.column1,table1.column2,table2.column1,....
FROM table1 
INNER JOIN table2
ON table1.matching_column = table2.matching_column;


table1: First table.
table2: Second table
matching_column: Column common to both the tables.

joining tables in sql

SELECT orders.order_Number, customers.First_Name, customers.Last_Name, customers.Address
FROM orders
INNER JOIN Customers ON orders.customers_id=customers.id;

join sql

#INNER JOIN: Intersection between 2 tables
SELECT *
FROM A
INNER JOIN B ON A.key = B.key

#LEFT JOIN: left table with the intersection joined to the right table
SELECT *
FROM A
LEFT JOIN B ON A.key = B.key

#LEFT JOIN(without intesection): left table without the intersection joined
#								to the right table
SELECT *
FROM A
LEFT JOIN B ON A.key = B.key
WHERE B.key IS NULL

#RIGHT JOIN: right table with the intersection joined to the left table
SELECT *
FROM A
RIGHT JOIN B ON A.key = B.key

#RIGHT JOIN(without intesection): right table without the intersection joined
#								to the left table
SELECT *
FROM A
RIGHT JOIN B ON A.key = B.key
WHERE A.key IS NULL # there seems to be a mistake on the site (B changed to A)

#FULL JOIN: union of 2 table
SELECT *
FROM A
FULL JOIN B ON A.key = B.key

#FULL JOIN(without intesection): union of two table without the intersection
SELECT *
FROM A
FULL JOIN B ON A.key = B.key
WHERE A.key IS NULL
OR B.key IS NULL