C# 如何使用数据库中的值设置标签文本？
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How do I set my label's text with a value from the database?
提问by Will_G
I got in my database a column "Klantnummer" and
I want that value as my label text.
How do I do that?
我在我的数据库中有一个“Klantnummer”列，
我希望该值作为我的标签文本。
我怎么做？
protected string conS = "Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Databees.mdf;Integrated Security=True;User Instance=True";
protected SqlConnection con;
protected void Page_Load(object sender, EventArgs e)
{
con = new SqlConnection(conS);
try
{
con.Open();
string q = "SELECT * FROM tblKLanten;";
SqlCommand query = new SqlCommand(q, con);
SqlDataReader dr = query.ExecuteReader();
Label1.Text = ; //I want here the value of klantnummer
con.Close();
}
catch (Exception ex)
{
Label2.Text = "Error";
}
}
采纳答案by Zeeshan
you can use:
您可以使用：
label1.Text = dr["Klantnummes"].ToString();
回答by Mike Perrenoud
Well, with the information provided it's not terribly easy to answer, but let's assumeyour structure is like this:
好吧，根据所提供的信息，回答起来并不容易，但让我们假设您的结构是这样的：
CREATE TABLE tblKLanten (
ID INT,
Klantnummer VARCHAR(50)
)
you'll need to get the field by the index from the reader like this:
您需要通过阅读器的索引获取字段，如下所示：
Label1.Text = dr.GetString(1);
but you're also going to need to read, so you'll need to issue this statement before setting the label:
但是您还需要阅读，因此您需要在设置标签之前发出以下声明：
bool success = dr.Read();
if (success)
{
// set the label in here
}
but remember, it's based off of the index of the column in the returned statementand so since you're issuing a SELECT *there's no way for me to know what the index is. In the end, I would recommend making some more changes, so consider the following code:
但请记住，它基于返回语句中列的索引，因此由于您发出的是一个SELECT *，我无法知道索引是什么。最后，我建议进行更多更改，因此请考虑以下代码：
protected string conS = "Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Databees.mdf;Integrated Security=True;User Instance=True";
protected SqlConnection con;
protected void Page_Load(object sender, EventArgs e)
{
con = new SqlConnection(conS);
try
{
con.Open();
string q = "SELECT * FROM tblKLanten;";
SqlCommand query = new SqlCommand(q, con);
using (SqlDataReader dr = query.ExecuteReader())
{
bool success = dr.Read();
if (success)
{
Label1.Text = dr.GetString(1);
}
}
con.Close();
}
catch (Exception ex)
{
Label2.Text = "Error";
}
}
the usingstatement there will make sure that the SqlDataReadergets disposed properly.
using那里的声明将确保SqlDataReader正确处理。
