如何检索ADO.NET SqlCommand的结果? [英] How do I retrieve the result of an ADO.NET SqlCommand?

问题描述

好吧，现在我真的很累还是很胖，但是我似乎找不到答案

Ok either I'm really tired or really thick at the moment, but I can't seem to find the answer for this

我正在使用ASP.NET，我想查找表中的行数.

I'm using ASP.NET and I want to find the amount of rows in my table.

我知道这是SQL代码:select count(*) from topics，但是如何将它显示为数字呢?

I know this is the SQL code: select count(*) from topics, but how the HECK do I get that to display as a number?

我要做的就是运行该代码，如果它= 0，则显示一件事，但如果它大于0，则显示另一件事.请帮忙吗?

All I want to do is run that code and if it = 0 display one thing but if it's more than 0 display something else. Help please?

这是我到目前为止所拥有的

This is what I have so far

string selectTopics = "select count(*) from topics";
// Define the ADO.NET Objects
SqlConnection con = new SqlConnection(connectionString);
SqlCommand topiccmd = new SqlCommand(selectTopics, con);
if (topiccmd == 0)
    {
        noTopics.Visible = true;
        topics.Visible = false;
    }

但是我知道我错过了严重的错误.我一直在寻找年龄，但找不到任何东西.

but I know I'm missing something seriously wrong. I've been searching for ages but can't find anything.

PHP非常简单. :)

PHP is so much easier. :)

推荐答案

请注意，必须先打开连接并执行命令，然后才能访问SQL查询的结果. ExecuteScalar返回一个单个结果值(如果查询将返回多列和/或多行，则必须使用不同的方法).

Note that you must open the connection and execute the command before you can access the result of the SQL query. ExecuteScalar returns a single result value (different methods must be used if your query will return an multiple columns and / or multiple rows).

请注意使用using构造，该构造将安全地关闭并释放连接.

Notice the use of the using construct, which will safely close and dispose of the connection.

string selectTopics = "select count(*) from topics";
// Define the ADO.NET Objects
using (SqlConnection con = new SqlConnection(connectionString))
{
   SqlCommand topiccmd = new SqlCommand(selectTopics, con);
   con.Open();
   int numrows = (int)topiccmd.ExecuteScalar();
   if (numrows == 0)
    {
        noTopics.Visible = true;
        topics.Visible = false;
    }
}

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