declare @squery varchar(max)
set @squery =   'if('+CHAR(39)+@AppendType+CHAR(39)+' = ''Address'')
begin
    update tblchild set name=(REPLACE(LEFT(phone,2)+LEFT(a,1),' ',''))
    update a  set a.a=a.name,a.name = b.name,a.email= b.email,a.b = '1' from tblchild as a , tblmaster as b where a.phone = b.phone
    update a  set a.name = b.name,a.phone = b.phone,a.a=b.a,a.b = '1' from tblchild as a , tblmaster as b where a.email = b.email and (a.b IS NULL or a.b = '')
end'

print(@squery)
exec (@squery)

select * from tblchild

name    email          phone            a   b
----------------------------------------------
s       z@a.in          111            NULL 1
u       a@ghf.ij        222            NULL 1
x       qww             333            NULL 1
ik      k@gmail.com     1234567890     NULL 1
kinjal  kin@abc.com     7894561230     NULL 1

declare @squery nvarchar(max)
declare @AppendType nvarchar(max) = N'Address'

set @squery =   N'if('+CHAR(39)+@AppendType+CHAR(39)+N' = ''Address'')
begin
    update tblchild set name=(REPLACE(LEFT(phone,2)+LEFT(a,1),'' '',''''))
    update a  set a.a=a.name,a.name = b.name,a.email= b.email,a.b = ''1'' from tblchild as a , tblmaster as b where a.phone = b.phone
    update a  set a.name = b.name,a.phone = b.phone,a.a=b.a,a.b = ''1'' from tblchild as a , tblmaster as b where a.email = b.email and (a.b IS NULL or a.b = '''')
end'

print(@squery)
execute sp_executesql @squery

select * from tblchild

update tblchild set name=(REPLACE(LEFT(phone,2)+LEFT(ISNULL(a,''''),1),'' '',''''))

update tblchild set name=(REPLACE(LEFT(phone,2)+LEFT(a,1),' ',''))