如何检查SQL中是否可用的表中的值? [英] how to check the values in the table which is avail or not in sql?

问题描述

用于登录....我在注册表中将值输入为rollno.

for login.... i entered the values as rollno in the registration table. how could i chek the input for login, entering rollno with the values present in the registration table?

推荐答案

private void txtCourseName_Leave(object sender, EventArgs e)
        {
            SqlCon = DBCon.DBOpenConnection();
            Query = "Select distinct Name from tblDepartmentMaster";
            SqlCmd = new SqlCommand(Query, SqlCon);
            SqlDr = SqlCmd.ExecuteReader();
            while (SqlDr.Read())
            {
                txtName.Text = SqlDr.GetString(0).ToString();
            }
            MessageBox.Show("Already Exist the Name!", "Already Exist", MessageBoxButtons.OK, MessageBoxIcon.Information);
            txtCourseName.Clear();
            ActiveControl = txtCourseName;

            SqlDr.Close();

        }

if (btnSave.Text == "Save")
        {
            SqlCommandBuilder cmdbSection;
            DataRow newrow;
            ds = new DataSet();
            ad = new SqlDataAdapter("select strTestName from PEHMstTest where strTestName='" + txttestname.Text + "'", SqlCon);
            ad.Fill(ds);
            if (ds.Tables[0].Rows.Count == 0)
            {
                DataSet ds1 = new DataSet();
                SqlDataAdapter ad1 = new SqlDataAdapter("select * from PEHMstTest", SqlCon);
                ad1.Fill(ds1);
                newrow = ds1.Tables[0].NewRow();
                newrow[0] = new_num();
                newrow[1] = txttestname.Text;
                newrow[2] = txtcharges.Text;

                ds1.Tables[0].Rows.Add(newrow);
                cmdbSection = new SqlCommandBuilder(ad1);
                ad1.Update(ds1);

                lblMsg.ForeColor = Color.Green;
                lblMsg.Text = "Records saved successfully";
            }
            else
            {
                lblMsg.ForeColor = Color.Red;
                lblMsg.Text = "Test Detail Already Exists, Give a different name.";
            }
           
        }

[edit]添加了前置标记[/edit]

[edit]added pre tag[/edit]

DataSet ds = new DataSet();
            SqlDataAdapter ad = new SqlDataAdapter("select * from technicalregistration where strloginname='" + txtusername.Text + "' and strloginpwd='" + txtpassword.Text + "'", sqlcon);
            ad.Fill(ds);
            if (ds.Tables[0].Rows.Count > 0)
            {
                Response.Redirect("Somepage.aspx");
            }
            else
                lblmessage.Text = "Invalid UserName and Password";

            txtusername.Text = "";
            txtpassword.Text = "";

你可以去这里

添加了前置标记[/编辑]

You can go for this

added pre tag[/Edit]

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