Equi Join, Natural Join, Cross Join

general discussion
1

Hello

Today it was happen that me and my friend was discussing on these joins. But we came up with no satisfactory answer.

Could some one please help us in understanding the exact differences between these joins. thanks in advance.

aniketp :uk: (BOB member since 2007-10-05)

2

Did you google?

Jansi :india: (BOB member since 2008-05-12)

3

This is for SQL Server2005 :

Arjun (BOB member since 2008-07-28)

4

Arjun, thanks a lot for the link. It was very helpful. I tried to understand it, but I couldn’t get any working example for the same.

If possible, can you please give me examples for equi join, natural join and cross join… thanks in advance.

aniketp :uk: (BOB member since 2007-10-05)

5

There should be no confusion between Natural and cross and equi and cross.

Because Cross join is A simple cartesian product.

Well.Natural and Equi differ only based on ur colum you select for joining,

Equi is same as Inner join .

Natural join will give you matching data for the colums you selected for joining .

I hope its clear :wave: :wave:

Well…One question i had everytime in my mind is Why Left outer and right outer join ??

One can use any one why two and everytime people say if table is to left you can use left outer and still no satisfactory till now.

:crazy_face: :crazy_face: :crazy_face:

Disha :uk: (BOB member since 2007-05-23)

6

Big difference between LEFT and RIGHT outer joins :slight_smile:

Namely, LEFT includes all records from the LEFT table, plus matching records from the right…and RIGHT outer join includes all records from the RIGHT table.

I may have got that the wrong way round, I always forget, but either way, they are fundamentally different joins and will return different data.

cashworth (BOB member since 2005-02-09)