What does the following SQL statement return, assuming that
all tables and column names are correct?
SELECT FirstName, StreetAddress
FROM Employees
JOIN AddressBook
ON Employees.EmpID = AddressBook.EmpID
a) Nothing, the JOIN syntax is wrong.
b) All the records form the Employees table, and only the
matching ones form the StreetAddress table.
c) All the records from the StreetAddress table and only the
matching records form the Employees table.
d) Only the matching records from the two tables.
Answer Posted / shikhar
I think the state ment above should return the records from
matching records from two talbes since the JOIN state ment
specifies the middle element..i.e employee...let us see how
it works..
lets say we hav two elemt rows( here i am taking the only
one column from each table since it would provide us with
the required understanding....)
employees addressbook
---------- ------------
EMP_NAME EMP_NAME
-------- -----------
ram raju
raj harish
ravi hani
rohit jitender
raju fina
manish kittu
now when these two statements are joined ,first of all the
first state ment is scanned and its first element i.e 'ram'
is matched againest the all the element of thhe other list
i.e addressbook...if it finds the name 'ram' in addressbook
it will select it as a part of the result otherwise it just
looks move on to another one thats 'raj'...n one important
thing ... in case 'ram' finds the match in the addressbook
twice...it will not take bothe of them .....it will skip
all the others and move on to the next row....
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