sql issue, oralc and sql server

Question

3.67/5 (2 votes)

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hi guys, i have a issue with sql, that is when we use "select", i think there're always 2 methods ,

SQL

select 
 name.t1,name.t2,name.t3 
from 
 t1,t2,t3 
where 
 t1.id=t2.id and t2.id=t3.id

or

SQL

select 
 name.t1,name.t2, name.t3 
from 
 t1
inner join t2 on t1.id=t2.id 
inner join t3 on t2.id=t3.id

so,
1.what's the differences between the 2 methods of select ?

2.if we use the 1st method, in oracle, we can use(+) to achieve left or right join, but in sql server or mysql or mb other database, how can we achieve left join in using the 1st method?

thanks in advance!

Posted 31-Mar-14 0:25am

v03051435

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2 solutions

Solution 2

To use left outer join in short hand mode, try using * symbol.
E.g. Where a.col1 *= b.col1

Posted 31-Mar-14 2:12am

Abhinav S

Comments

v03051435 1-Apr-14 4:05am

thanks Abhinav, i have another question, what's the diff between :
select t1.name,t2.name,t3.name
from t1
left join t2 on t1.id=t2.id
(and/where) t2.name='aa'
i noticed that "and or where" make different result, so what's the difference? thank you

Abhinav S 1-Apr-14 4:16am

And adds two sets of conditions. Where is to indicate filters on the table.

Abhinav S 1-Apr-14 4:16am

Vote if this answer helped.

v03051435 1-Apr-14 5:28am

thanx for ur reply and i voted, but i found a better answer too for u :

http://stackoverflow.com/questions/354070/sql-join-where-clause-vs-on-clause

that's what i mean :)

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Er. Puneet Goel · Accepted Answer · 2014-03-31T02:09:00

Solution 1

You have some wrong syntax here. It should be like table.Coluumn not column.table

SQL

select
 t1.name,t2.name,t3.name
from
 t1,t2,t3
where
 t1.id=t2.id and t2.id=t3.id

Ans1: The first one is short hand(also the old method) so doing this while later one is the detailed way and much readable.

Ans2:

SQL

select t1.name,t2.name,t3.name
from t1
 left join t2 on t1.id=t2.id
 left join t3 on t2.id=t3.id

Posted 31-Mar-14 2:09am

Er. Puneet Goel

Comments

v03051435 31-Mar-14 8:52am

hi,Goel, thanks for ur reply, if i wanna use short hand and left join in the same time, how to achieve? like "Where a.col1 *= b.col1"? and there is no influence of matenance between "short hand" and "writing left join each time" method? thanks for ur reply.

Er. Puneet Goel 31-Mar-14 8:56am

this is simple

select a.name,b.name,c.name
from table1 a
left join table2 b on a.id=b.id where b.name = 'abc'
left join table3 c on b.id=c.id where c.name = 'abc'
Where a.name='axyz'