c# - define minimum length column in xsd -

I am trying to generate an XSD based on the database created in vs.net 2008. How can I specify the minimum duration for my column in xsd? Xsd: ban base = 'xsd: string' & gt; & Lt; Xsd: minlang value = '0' / & gt; & Lt; Xsd: maxLength value = '50 '/ & gt; & Lt; / XSD: Ban & gt;