||SQL Server Tips by Burleson
Char stores fixed length ASCII data. The data is padded with spaces
on the right as this example shows:
DECLARE @b char(10)
SELECT CAST(@b as binary(10))
The 202020… are a sequence of spaces. 20 is the hexadecimal
representation of the space character.
Note: An interesting detail is that char can actually store
non-ASCII data. In the previous example let us replace the second
line with this one:
The three bytes are there, although not visible when displayed.
The above book excerpt is from:
Turbocharge Database Performance with C++ External Procedures
Joseph Gama, P. J. Naughter