Introduction
The SqlParameter class is found in the
"System.Data.SqlClient" namespace. It is a class of a connected architecture of
.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 SqlParameter class. Here is a list of
important properties of the SqlParameter class which will be used in this example.
SqlDbType :
It is used to set the Sql Server Data types for a given
parameter.
ParameterName :
It is used to specify a parameter name.
Direction : It is used for setting the direction
of a SqlParameter. It is Input or Output or both (InputOutput).
Size : It is used to set maximum size of
value of parameter.
Value : It is used for
assigning or getting 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.