如何在c＃windows应用程序中从数据库中检索数据 [英] how to retrieve data from database in c# windows application

问题描述

private void button2_Click(object sender, EventArgs e)
        {
            SqlConnection con = new SqlConnection("Data Source=ROHIT-PC\\SQLEXPRESS;Initial Catalog=FMS;Integrated Security=True");
          
             SqlCommand cmd = new SqlCommand("select * from JUNIOR_STUDENT where @UID='+ @ " + txtUid.Text.Trim() + "'",con);
             cmd.CommandType = CommandType.Text;
             cmd.Parameters.AddWithValue("@UId", txtUid.Text);
             cmd.Parameters.AddWithValue("@NAME", txtName.Text);
             cmd.Parameters.AddWithValue("@ROLL_NO", txtRoll.Text);
             cmd.Parameters.AddWithValue("@STREAM", txtStream.Text);
             cmd.Parameters.AddWithValue("@GENDER", txtGender.Text);
             cmd.Parameters.AddWithValue("@YEAR_ID", cbxYearname.Text);
             cmd.Parameters.AddWithValue("@REMARKS", txtRemarks.Text);
             cmd.Parameters.AddWithValue("@ADMISSION_DATE", mtxtAdmsndate.Text);
             cmd.Parameters.AddWithValue("@ACADEMIC_YEAR", txtAcademicYear.Text);
             cmd.Parameters.AddWithValue("@ADMISSION_TYPE", txtAdmissiontype.Text);
             cmd.Parameters.AddWithValue("@CATEGORY_ID", cbxCategory.Text);
             cmd.Parameters.AddWithValue("@SUB_CATEGORY", txtName.Text);
             cmd.Connection = con;
             con.Open();
             
             SqlDataReader reader = cmd.ExecuteReader();
              while (reader.Read())
              {
              txtName.Text=reader["NAME"].ToString();
              txtRoll.Text = reader["ROLL_NO"].ToString();
              txtStream.Text = reader["STREAM"].ToString();
              txtGender.Text = reader["GENDER"].ToString();
              cbxYearname.Text = reader["YEAR_ID"].ToString();
              txtRemarks.Text = reader["REMARKS"].ToString();
              mtxtAdmsndate.Text = reader["ADMISSION_DATE"].ToString();
              txtAcademicYear.Text = reader["ACADEMIC_YEAR"].ToString();
              txtAdmissiontype.Text = reader["ADMISSION_TYPE"].ToString();
              cbxCategory.Text = reader["CATEGORY_ID"].ToString();
              txtSubcategory.Text = reader["SUB_CATEGORY"].ToString();
              
              
              reader.Close();
              con.Close();
              MessageBox.Show("Student : " + txtName.Text + " Transfer of Subject Successfull ", "Student Information", MessageBoxButtons.OK, MessageBoxIcon.Information);
           }
                  }

它没有显示我能做什么？

it show nothing wat can i do ??

推荐答案

你没有提供足够的信息你的问题。



读者是否包含任何内容？没有！查看您的查询：

You did not provide enough information about your issue.

Does the reader contains anything? No! Have a look at your query:

"select * from JUNIOR_STUDENT where @UID='+ @ " + txtUid.Text.Trim() + "'"

您的查询应该是：

Your query should be:

select [Name], RollNo, Stream, Gender, Year_ID, Remarks, Admission_Date, Academic_Year, Admission_tye, Category_ID, Sub_Category
from JUNIOR_STUDENT
where UID=@UID

最后，你只使用ine参数 @UID ，那么为什么要设置 [Name] ， Rollno 等等？



BTW：名字是保留字，用括号括起来！



更正的代码：

Finally, you are using only ine parameter @UID, so why do you set [Name], Rollno, etc?

BTW: Name is a reserved word, use it with brackets!

Corrected code:

SqlCommand cmd = new SqlCommand("select * from JUNIOR_STUDENT where UDI=@UID",con);
             cmd.CommandType = CommandType.StoredProcedure;
             cmd.Parameters.AddWithValue("@UId", txtUid.Text);
             con.Open();
             SqlDataReader reader = cmd.ExecuteReader();

这是一个基本想法：如何：使用Visual C＃.NET在ASP.NET中调用SQL Server存储过程 [ ^ ]。这是真的，它是ASP.NET，但逻辑是一样的！

Here is a basic idea: HOW TO: Call SQL Server Stored Procedures in ASP.NET by Using Visual C# .NET[^]. It's true, it's ASP.NET, but the logic is the same!

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