字符串前面的大写字母全部转成小写
将keyColumn开始的所有大写字母转成小写
string nColumn = string.Empty;
foreach (char c in keyColumn)
{
if (c > 'A' && c < 'Z')//判断是否为大写
nColumn += c.ToString().ToLower();
else
break;
}
if (keyColumn.Length > nColumn.Length)
nColumn += keyColumn.Substring(nColumn.Length);