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.Keysql join
-- Rows with ID existing in both a, b and c
-- JOIN is equivalent to INNER JOIN
SELECT a.ID, a.NAME, b.VALUE1, c.VALUE1 FROM table1 a
JOIN table2 b ON a.ID = b.ID
JOIN table3 c ON a.ID = c.ID
WHERE a.ID >= 1000;
-- ⇓ Test it ⇓ (Fiddle source link)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.left join sql
#LEFT JOIN: Return all rows from the left table, even if there are no matches in the right
#table
syntax->SELECT column_name(s)
FROM table_name1
LEFT JOIN table_name2
ON table_name1.column_name=table_name2.column_name
////example/////
SELECT Persons.LastName, Persons.FirstName, Orders.OrderNo
FROM Persons
LEFT JOIN Orders
ON Persons.P_Id=Orders.P_Id
ORDER BY Persons.LastNamejoin data in sql
#Joining 2 tables: table_1 and table_1
#Select the all the columns you want to show in the final joined table.
SELECT
table_1.column_a,
table_2.column_b
#Select the first table
FROM
database_name.table_1
#Select the type of join statement and second table you want to join.
JOIN
database_name.table_2
#Select the related columns on which you want to join the tables.
ON
table_1.column_a = table_2.column_bCopyright © 2021 Codeinu
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