create table test(
indkey nvarchar(2),
datakey nvarchar(4),
landline nvarchar(11),
mobile nvarchar(11),
email nvarchar(20))

insert into test
values ('1','0001','01234567890','0712345679','1@test.co.uk')
insert into test
values ('2','0001','01234567890','','1@test.co.uk')
insert into test
values ('3','0002','01234567891','','2@test.co.uk')
insert into test
values ('4','0002','01234567890','','2@test.co.uk')
insert into test
values ('5','0002','','07123456789','')
insert into test
values ('6','0003','01234567892','07123456791','')
insert into test
values ('7','0004','01234567893','07123456792','')
insert into test
values ('8','0005','01234567894','07123456793','2@test.co.uk')
insert into test
values ('9','0008','01234567895','07123456793','9@test.co.uk')

SELECT COUNT(*) AS Total,
       COUNT(DISTINCT datakey) AS Uniquedatakey,
       COUNT(DISTINCT CASE WHEN landline<>'' THEN landline END) AS Uniquelandline,
       COUNT(DISTINCT CASE WHEN mobile<>'' THEN mobile END) AS Uniquemobile,
       COUNT(DISTINCT CASE WHEN email<>'' THEN email END) AS Uniqueemail       
FROM test