C# c在不起作用的条件下

我没有犯错误 但是列表框显示未过滤的值我想要在时间和结束之间获取值

   String start_cd;
   String end_cd;
   int time_start_int;
   int time_end_int;
    opencon();

     SqlCommand res = new SqlCommand("SELECT ID,Available,Type," + start_cd + "," + end_cd + " FROM " + going + " WHERE " + start_cd + "!=0 or " + end_cd + "!=0 and " + start_cd + " >= " + time_start_int + " and " + start_cd + " <= " + time_end_int + "", con);
    SqlDataAdapter sda_res = new SqlDataAdapter(res);
    DataTable dt_res = new DataTable();
    sda_res.Fill(dt_res);

    listBox1.DataSource=dt_res;
    listBox1.DisplayMember="ID";

    listBox2.DataSource = dt_res;
    listBox2.DisplayMember = start_cd;

您错过了字符串变量的“单引号”。

您需要在单独的表达式中比较time\u start\u int和time\u end\u int与start\u cd，如下所示

SqlCommand res = new SqlCommand("SELECT ID,Available,Type,"'+ start_cd +'","' +
        end_cd +'" FROM going  
       WHERE "'+ start_cd +'"!=0 or "'+ end_cd +'"!=0 and " + 
       time_start_int + " <= "'+ start_cd +'" <= " + time_end_int + "", con);

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请记住，使用字符串连接SQL语句会使代码容易受到SQL注入攻击。您可以参考以获得一些关于如何避免SQL注入攻击的提示。

首先，我使用括号表示or，因为and将首先计算，可能会导致删除所有筛选器，在第二部分中，我写时间\u start\u int+人们已经在您前面的问题中告诉您，连接字符串以创建查询是一种老式且有风险的做法。即使您坚持编写带有SQL注入问题的代码，也请花点时间编辑您的示例，这样就不需要滚动，滚动示例以尝试猜测错误是不必要的困难。+0:虽然可能是正确的，但没有解释什么是错误的你做到了，更重要的是为什么。我在“FOT”附近得到了错误的语法。FOT=start\u cdI希望这些变化能为您提供一些关于我所做工作的线索。

SqlCommand res = new SqlCommand("SELECT ID,Available,Type," + start_cd + "," + 
    end_cd + " FROM " + going + 
   " WHERE " + start_cd + "!=0 or " + end_cd + "!=0 and " + 
   time_start_int + " <= " + start_cd + " and " +
   start_cd + " <= " + time_end_int + "", 
   con);

SqlCommand res = new SqlCommand("SELECT ID,Available,Type," + start_cd + "," + 
    end_cd + " FROM " + going + 
   " WHERE (" + start_cd + "!=0 or " + end_cd + "!=0 ) and " + 
   time_start_int + " <= " + start_cd + " and " + start_cd + " <= " + time_end_int + "", con);