tag:blogger.com,1999:blog-694855878384792308.post1568404032669596551..comments2024-03-21T06:26:49.387-07:00Comments on Java67: Difference between Self and Equi Join in SQL - INNER Join example MySQLjavin paulhttp://www.blogger.com/profile/15028902221295732276noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-694855878384792308.post-45187886665133439642022-08-18T13:44:36.340-07:002022-08-18T13:44:36.340-07:00Your query works in this simple example but in rea...Your query works in this simple example but in reality most managers are managed by someone else. Your query would probably produce one row and that would be the CEO. Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-694855878384792308.post-81705777672427354832016-09-15T20:22:27.775-07:002016-09-15T20:22:27.775-07:00excellent explanation.excellent explanation.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-694855878384792308.post-67926085727598513692016-01-26T08:40:32.475-08:002016-01-26T08:40:32.475-08:00Your query:
select distinct e.emp_id, e.emp_name f...Your query:<br /><b>select distinct e.emp_id, e.emp_name from employee e join employee m on e.emp_id=m.mgr_id;</b><br />is equal to this another one:<br /><br />select emp_id, emp_name from employee where emp_id=mgr_id; ???<br /><br />how can i do know when i have to use a SELF JOIN or a simple query on the table??<br /><br />Thx<br />sheldomhttps://www.blogger.com/profile/06972098120353128858noreply@blogger.comtag:blogger.com,1999:blog-694855878384792308.post-30864050851584188392015-09-05T10:21:46.071-07:002015-09-05T10:21:46.071-07:00nice bro....
nice bro....<br />Anonymoushttps://www.blogger.com/profile/15757747899016475522noreply@blogger.comtag:blogger.com,1999:blog-694855878384792308.post-80152577703307953722014-12-18T01:52:01.723-08:002014-12-18T01:52:01.723-08:00self join is quite useful when you want to join tw...self join is quite useful when you want to join two instances of same table. Like in your Employee schema, how do you write query to print name of employee and their manager? You can do this using self join as shown below :<br /><br /><b>SELECT e.emp_name, m.emp_name as manager FROM Employee where e.emp_id = m.mgr_id;</b><br /><br />Equi join is about condition, if your WHERE clause or ON JOIN condition uses = equal operator it's known as equi join, but if you use != or less than, greater than or any other condition, it will not call equi join. Vidhyanoreply@blogger.com