Providers that do not use a suffix character to escape the dbliteral escape percent character do not return this literal value and can set the lt member of the dbliteral structure to dbliteral invalid if requested 不使用后缀字符来转义dbliteral _ escape _ percent字符的提供程序不会返回此文本值，它们可以在需要时将dbliteral结构的lt成员设置为dbliteral _ invalid 。
