Why we use joins in SQL?

Muhammad Abdullah

10y1.1kSQL

Why we use joins in SQL? Please give any real world example.

4 Replies

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Pradeep Sahoo10y ago
Accepted answer
Join is needed when the required data is not in a single table . For example let's say bank account . Account information and customer information are two different entities . So they should be joined to get the data when account detailed information is needed to show on the page .
Roshan Guragain10y ago
If we want to retrieve data from two different table then we use joins in SQL.for example : If we have a table employee with attributes eid,ename and department with attributes deptid,eid.if we want another table containing eid,ename and deptid then we use joins..
Rajeesh Menoth10y ago
Hi,
A SQL JOIN combines records from two tables.
A JOIN locates related column values in the two tables.
A query can contain zero, one, or multiple JOIN operations.
INNER JOIN is the same as JOIN; the keyword INNER is optional.
Real World Example :

http://thomaslarock.com/2012/04/real-world-sql-join-examples/

Reference :

http://www.dofactory.com/sql/join

http://stackoverflow.com/questions/2241991/in-mysql-queries-why-use-join-instead-of-where
Amit Gupta10y ago
The SQL Joins clause is used to combine records from two or more tables in a database. A JOIN is a means for combining fields from two tables by using values common to each. Here, it is noticeable that the joinis performed in the WHERE clause.

You can go to the below link to get the thing more understandable.
http://www.w3schools.com/sql/sql_join.asp