--== Sample Data ==--
use tempdb
go

if object_id('tempdb..#Customer1') is not null drop table #Customer1
if object_id('tempdb..#Customer2') is not null drop table #Customer2
if object_id('tempdb..#Customer3') is not null drop table #Customer3

create table #Customer1
(
customer_name varchar(30),
address varchar(30),
city varchar(30)
)

insert into #Customer1 values ('Joe James', '43 Holgate St', 'York')
insert into #Customer1 values ('Ken Fletcher', '15 North St', 'Leeds')

create table #Customer2
(
customer_name varchar(30),
address varchar(30),
city varchar(30)
)

insert into #Customer2 values ('Joe James', 'Holgate St', 'York')
insert into #Customer2 values ('Ken Fletcher', '15 North St', 'Leeds')

create table #Customer3
(
customer_name varchar(30),
address varchar(30),
city varchar(30)
)

insert into #Customer3 values ('Joe James', '43 Holgate St', 'York')
insert into #Customer3 values ('Ken Fletcher', 'North St', 'Leeds')

--== Example to show result from joins ==--
Select 
	A.customer_name, A.address, A.city, 
	B.customer_name, B.address, b.city, 
	c.customer_name, c.address, c.city
from #Customer1 as A
	left join #Customer2 as B on left(A.customer_name,18) = left(B.customer_name,18) 
		and A.Address = B.Address and A.City = B.City
	left join #Customer3 as C on left(A.customer_name,18) = left(C.customer_name,18) 
		and A.Address = C.Address and A.City = C.City

--== Possible Solution ==--
Select 
	ISNULL(B.customer_name, C.customer_name) as customer_name,
	ISNULL(B.address, C.address) as address,
	ISNULL(B.city, C.city) as city
from #Customer1 as A
	left join #Customer2 as B on left(A.customer_name,18) = left(B.customer_name,18) 
		and A.Address = B.Address and A.City = B.City
	left join #Customer3 as C on left(A.customer_name,18) = left(C.customer_name,18) 
		and A.Address = C.Address and A.City = C.City