C# 在asp.net标签中显示SQL查询结果
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Display SQL query result in a label in asp.net
提问by Eximus
I'm trying to display the SQL query result in a label but it's not showing. This is my code:
我试图在标签中显示 SQL 查询结果，但没有显示。这是我的代码：
string result = "SELECT ACTIVE FROM [dbo].[test] WHERE ID = '" + ID.Text + "' ";
SqlCommand showresult = new SqlCommand(result, conn);
conn.Open();
showresult.ExecuteNonQuery();
string actresult = ((string)showresult.ExecuteScalar());
ResultLabel.Text = actresult;
conn.Close();
Need help please. Thanks!
需要帮助请。谢谢！
回答by CCBlackburn
Is there a typo in there? You have two calls to the database:
里面有错别字吗？您有两个对数据库的调用：
showresult.ExecuteNonQuery();
This won't return a value and I'm not sure why you would have it there
这不会返回值，我不确定你为什么要在那里
string actresult = ((string)shresult.ExecuteScalar());
Unless you have a shresult variable, this query should error. What is the shresult variable?
除非你有一个 shresult 变量，否则这个查询应该会出错。什么是 shresult 变量？
回答by hallie
Try this one.
试试这个。
string result = "SELECT ACTIVE FROM [dbo].[test] WHERE ID = '" + ID.Text + "' ";
SqlCommand showresult = new SqlCommand(result, conn);
conn.Open();
ResultLabel.Text = showresult.ExecuteScalar().ToString();
conn.Close();
回答by adatapost
Use SqlParameterto filter the result and call ExecuteScalar()or ExecuteReader()method.
使用SqlParameter过滤结果和呼叫ExecuteScalar()或ExecuteReader()方法。
string result = "SELECT ACTIVE FROM [dbo].[test] WHERE ID=@ID";
SqlCommand showresult = new SqlCommand(result, conn);
// If ID is int type
showresult.Parameters.Add("@ID",SqlDbType.Int).Value=ID.Txt;
// If ID is Varchar then
//showresult.Parameters.Add("@ID",SqlDbType.VarChar,10).Value=ID.Txt;
conn.Open();
string actresult = (string)showresult.ExecuteScalar();
conn.Close();
if(!string.IsNullOrEmpty(actresult))
ResultLabel.Text = actresult;
else
ResultLabel.Text="Not found";
回答by JP Hellemons
using (SqlConnection conn = new SqlConnection(connectionString))
{
string result = "SELECT ACTIVE FROM [dbo].[test] WHERE ID = @id";
SqlCommand showresult = new SqlCommand(result, conn);
showresult.Parameters.AddWithValue("id", ID.Text);
conn.Open();
ResultLabel.Text = showresult.ExecuteScalar().ToString();
conn.Close();
}
This will dispose the connection and has no string concatenation in the query.
这将处理连接并且在查询中没有字符串连接。
回答by Govind Tiwari
conn.Open();
string result = "SELECT ACTIVE FROM test WHERE ID = '" + ID.Text + "' ";
SqlCommand showresult = new SqlCommand(result, conn);
showresult.ExecuteNonQuery();
int actresult = ((int)showresult.ExecuteScalar());
ResultLabel.Text = actresult.Tostring();
conn.Close();
