string[] strs={"1","2","3","4","5","6","7","8","9"}
               bool[] bs = { s1, s2,s3,s4,s5,s6,s7,s8,s9 };
               for (int i = 0; i < bs.Length; i++)
                {
                    if (bs[i]) 条件为TRUE 进入
                    {
                        builder.Append(strs[i]);
                        builder.Append(" and "); //问题在这里 最后一个为TRUE时不运行这句 
                    }                }bs[i] 只有一个TRUE时 builder.Append(strs[i]);
bs[i] 如果有多个TRUE 最后不运行builder.Append(" and "); 这段
我用这个循环来填充SQL语句