If you're storing phone numbers in a float typed column (which is a bad idea) then they are presumably all integers and could be cast to int before casting to nvarchar.
So instead of:
select cast(cast(1234567890 as float) as nvarchar(50))
1.23457e+009
You would use:
select cast(cast(cast(1234567890 as float) as int) as nvarchar(50))
1234567890
In these examples the innermost cast(1234567890 as float)
is used in place of selecting a value from the appropriate column.
I really recommend that you not store phone numbers in floats though!
What if the phone number starts with a zero?
select cast(0100884555 as float)
100884555
Whoops! We just stored an incorrect phone number...