Working With the SqlParameter Class in ADO.NET

Introduction

 

The SqlParameter class is found in the "System.Data.SqlClient" namespace. It is a class of a connected architecture of the .NET framework. It represents parameters. To work with the SqlParameter class we should have a database. In this example, I am using a Database "student" which has a "student_detail" table. "RollNo", "Name" and "City" are column names. I will save and retrieve records using the SqlParameter class.  Here is a list of important properties of the SqlParameter class which will be used in this example.

1. SqlDbType: It is used to set the SQL Server Datatypes for a given parameter.
   
2. ParameterName: It is used to specify a parameter name.
3. Direction: It is used for setting the direction of a SqlParameter. It is Input or Output or both (InputOutput).
4. Size: It is used to set the maximum size of the value of the parameter.
   
5. Value: It is used for assigning or getting the value of the parameter.

Now, take a Windows Forms application in Visual Studio 2010. Take some UI Controls and arrange them as shown in the figure below

 

 

Write the following code for saving a record into the database.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;
namespace WorkWithSqlParameterClass {
    public partial class Form1: Form {
        public Form1() {
            InitializeComponent();
        }

        SqlConnection conn;
        SqlCommand comm;
        string connstring = "database=student;server=.;user=sa;password=wintellect";

        private void btnsave_Click(object sender, EventArgs e) {
            conn = new SqlConnection(connstring);
            conn.Open();

            comm = new SqlCommand();
            comm.Connection = conn;

            //Creating instance of SqlParameter
            SqlParameter PmtrRollNo = new SqlParameter();
            PmtrRollNo.ParameterName = "@rn"; // Defining Name
            PmtrRollNo.SqlDbType = SqlDbType.Int; // Defining DataType
            PmtrRollNo.Direction = ParameterDirection.Input; // Setting the direction

            //Creating instance of SqlParameter
            SqlParameter PmtrName = new SqlParameter();
            PmtrName.ParameterName = "@nm"; // Defining Name
            PmtrName.SqlDbType = SqlDbType.VarChar; // Defining DataType
            PmtrName.Direction = ParameterDirection.Input; // Setting the direction

            //Creating instance of SqlParameter
            SqlParameter PmtrCity = new SqlParameter();

            PmtrCity.ParameterName = "@ct"; // Defining Name
            PmtrCity.SqlDbType = SqlDbType.VarChar; // Defining DataType
            PmtrCity.Direction = ParameterDirection.Input; // Setting the direction

            // Adding Parameter instances to sqlcommand

            comm.Parameters.Add(PmtrRollNo);
            comm.Parameters.Add(PmtrName);
            comm.Parameters.Add(PmtrCity);

            // Setting values of Parameter

            PmtrRollNo.Value = Convert.ToInt32(txtrollno.Text);
            PmtrName.Value = txtname.Text;
            PmtrCity.Value = txtcity.Text;

            comm.CommandText = "insert into student_detail values(@rn,@nm,@ct)";

            try {
                comm.ExecuteNonQuery();
                MessageBox.Show("Saved");
            } catch (Exception) {
                MessageBox.Show("Not Saved");
            } finally {
                conn.Close();
            }
        }
    }
}

Run the application.

 

Output

 

 

Fill in the form and click the "Save" button. The record will be saved to the database and a message box will be displayed with a confirmation message.

 

 

Now we retrieve records from the database. Take another button and set its text property as "Show". Add the following code for the "Show" button. 

private void btnshow_Click(object sender, EventArgs e) {
    conn = new SqlConnection(connstring);
    conn.Open();

    comm = new SqlCommand();
    comm.Connection = conn;

    //Creating instance of SqlParameter
    SqlParameter PmtrRollNo = new SqlParameter();
    PmtrRollNo.ParameterName = "@rn"; // Defining Name
    PmtrRollNo.SqlDbType = SqlDbType.Int; // Defining DataType
    PmtrRollNo.Direction = ParameterDirection.Input; // Setting the direction

    //Creating instance of SqlParameter
    SqlParameter PmtrName = new SqlParameter();
    PmtrName.ParameterName = "@nm"; // Defining Name
    PmtrName.SqlDbType = SqlDbType.VarChar; // Defining DataType
    PmtrName.Size = 30;
    PmtrName.Direction = ParameterDirection.Output; // Setting the direction

    //Creating instance of SqlParameter
    SqlParameter PmtrCity = new SqlParameter("@ct", SqlDbType.VarChar, 20);
    PmtrCity.Direction = ParameterDirection.Output; // Setting the direction

    // Adding Parameter instances to sqlcommand

    comm.Parameters.Add(PmtrRollNo);
    comm.Parameters.Add(PmtrName);
    comm.Parameters.Add(PmtrCity);

    // Setting values of Parameter

    PmtrRollNo.Value = Convert.ToInt32(txtrollno.Text);
    PmtrName.Value = txtname.Text;
    PmtrCity.Value = txtcity.Text;

    comm.CommandText = "select @nm=name,@ct=city from student_detail where rollno=@rn";

    try {
        comm.ExecuteNonQuery();
        txtname.Text = PmtrName.Value.ToString();
        txtcity.Text = PmtrCity.Value.ToString();
    } catch (Exception) {
        MessageBox.Show("Not Found");
    } finally {
        conn.Close();
    }
}

Run the application.

 

Output

 

 

Enter a roll number and click the "Show" button. It will show all the related information of the student having the given roll number.

 

 

Here are some related resources.

• Save, Delete, Search And Update Record Using SqlParameter Class in ADO.NET
• Working With AutoIncrement Property of DataColumn Class in ADO.NET
• DataRelation class in ADO.NET
• Working with the SqlTransaction Class in ADO.NET
• ADODB Services in .NET Applications Using C#