如何在过滤搜索ASP.NET C＃后检查是否找到任何记录 [英] How do I check if there are any records found after filter search ASP.NET C#

问题描述

我不确定如何检查select是否从数据库返回任何行。如果没有找到行，我想要一条错误消息



我尝试过：

I am unsure how to check if select returns any rows from database. I want to have an error message if there are no rows found

What I have tried:

try
        {
            string strConnString = ConfigurationManager.ConnectionStrings["ConnStr"].ConnectionString;
            SqlConnection con = new SqlConnection(strConnString);
            DataTable dt = new DataTable();

            using (SqlConnection conn = new SqlConnection(strConnString))
            {
                string strQuery = "SELECT * FROM TDLoanRate where LoanType Like'" + txtValue.Text + "%'";
                SqlCommand cmd = new SqlCommand(strQuery);
                using (SqlDataAdapter sda = new SqlDataAdapter())
                {
                    cmd.Connection = con;
                    conn.Open();
                    sda.SelectCommand = cmd;
                    sda.Fill(dt);
                    GridView2.DataSource = dt;
                    GridView2.DataBind();
                } 

推荐答案

int count = dt.Rows.Count; // get the count 

您的代码容易受到 SQL注入 [ ^ ]攻击。

始终使用参数化查询以防止SQL Server中的SQL注入攻击 [ ^ ]

Your code is vulnerable to SQL injection [^] attacks.
Always use Parameterized queries to prevent SQL Injection Attacks in SQL Server[^]

<如果计数> br />

只需从特定表中获取计数1然后有记录找到，其他明智的是没有找到记录。

simply get count from particular table if count > 1 then there is record found, other wise there is no record found.

如果我想检查是否有客户那么我会做什么



i将计算



从客户中选择计数（1）



存储该值在任何变量中检查你想要的条件。

假设我将值存储在字符串s中;

if（convert.int32（s）> 0）

{



}

if i want to check is there any customer then what i will do

i will count

select count(1) from customers

store that value in any variable and check what ever condition you want.
suppose i store value in string s;
if(convert.int32(s)>0)
{

}

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