CODEWITHSUNDEEP
sqloracle-databasejoin
Saqib Shaukat
Saqib Shaukat

Reputation: 47

Oracle: Multiple joins

can anybody explain how this multiple joins works? Primary Key of A goes to Table B as foreign key while Primary key of B goes to C as foreign key. Thanks in advance. 

Table A         TABLE B (has fk of A)               TBALE C (HAS FK OF B)
aid  aname      bid bname afk                       cid  cname bfk
 1   a           1   b      1                       1     c     1
 2  a2           2   b2     2                       2     c2     1

select a.aname , b.bname , c.cname from A a
left join B b
on a.aid = b.afk
left  join C c 
on c.bfk = b.bid;

Upvotes: 1

Views: 295

Answers (1)

SandPiper
SandPiper

Reputation: 2906

You will end up with the following result set:

a   b   c
a   b   c2
a2  b2  Null

You have no entry for the cname in the third record because there is no record in table c that has a bfk of 2.

Upvotes: 1

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