String formatting does not behave as expected when using padding

I am trying to form a text representation of a table based off of the result coming in from a SqlDataReader.

while (unitsRdr.Read())
{
    note.AppendFormat("{0,-15}", String.Format("{0}({1})", unitsRdr.GetValue(0), unitsRdr.GetValue(1)));
}

Now what I expect to happen is I should get 4 sets of items, that will have padding on the right hand side equal to 15. Like this

BP(mm\Hg)      HR(bpm)        RR(rpm)        Sa O2(%)       |<-- this would be th开发者_Python百科e end of the string.

However what I am getting is

BP(mm\Hg          )HR(bpm            )RR(rpm            )Sa O2(%              )|<-- this is the end of the string.

It appears to start counting after the ( and the ) is put after the number of spaces.

What is the correct way of doing formatting so the text is like my first example?

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For anyone who wants it here is the source table

desc         unit
------------ ----------
BP           mm\Hg     
HR           bpm       
RR           rpm       
Sa O2        %         

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I strongly suspect that the problem is that the value returned by unitsRdr.GetValue(1) is actually longer than you believe. I very much doubt that string.Format is doing that. Try using unitsRdr.GetValue(1).Trim() instead - or just test it with a hard-coded literal value.