SqlParameter represents a parameter to a SqlCommand and optionally its mapping to DataSet columns. Parameter names are not case sensitive.
To initialize a new instance of SqlParameter class, we can use many constructors such as SqlParameter(), SqlParameter(String, SqlDbType), SqlParameter(String, Object), SqlParameter(String, SqlDbType, Int32), SqlParameter(String, SqlDbType, Int32, String).
SqlParameter() constructor initialize a new instance of SqlParameter class. Sqlparameter(String, SqlDbType) constructor require parameter name and data type. SqlParameter(String, Object) constructor require parameter name and a value of the new SqlParameter. SqlParameter(String, SqlDbtype, Int32) constructor require parameter name, SqlDbType and size. SqlParameter(String, SqlDbtype, Int32, String) constructor require parameter name , SqlDbType, size and the source column name.
SqlParameter class have many useful properties such as CompareInfo, DbType, Direction, IsNullable, Offset, ParameterName, Precision, Scale, Size, SourceColumn, SqlDbType, SqlValue, TypeName, Value, XmlSchemaCollectionName etc.
ParameterName property get or set the SqlParameter name. SqlDbType property get or set the SqlDbType (SQL Server specific data type) for the parameter. SqlDbType enumeration values are BigInt, Binary, Bit, Char, Date, DateTime, Decimal, Float, Image, Int, Money, Real, Text, Time, Timestamp etc. SqlParameter Size property get or set the maximum size in bytes of the data within the column. Direction property get or set a value that indicate whether the parameter is input only, output only, bidirectional or a stored procedure return value parameter. Value property get or set the value of parameter.
The following c# example source code describe you more about SqlParameter in ASP.NET.
Create a web form name SqlParameterExample.aspx. Now add a GridView control. We populate the GridView control with SqlDataSource Data. But here we filter the data by SqlParameter. In this example we select the NorthWind database Products table data and filter it with SqlParameter product name. The source code of SqlParameterExample.aspx is here.
<%@ PageLanguage="C#" %>
<%@ ImportNamespace="System.Data" %>
<%@ ImportNamespace="System.Data.SqlClient" %>
<%@ ImportNamespace="System.Configuration" %>
<!DOCTYPE html>
<script runat="server">
protectedvoidPage_Load(object sender, System.EventArgs e) {
if (!Page.IsPostBack) {
SqlConnection MyConnection;
SqlCommand MyCommand;
SqlDataReader MyReader;
SqlParameter ProductNameParam;
MyConnection = new SqlConnection();
MyConnection.ConnectionString = ConfigurationManager.ConnectionStrings["AppConnectionString1"].ConnectionString;
MyCommand = new SqlCommand();
MyCommand.CommandText = "SELECT * FROM PRODUCTS WHERE PRODUCTNAME = @PRODUCTNAME";
MyCommand.CommandType = CommandType.Text;
MyCommand.Connection = MyConnection;
ProductNameParam = new SqlParameter();
ProductNameParam.ParameterName = "@PRODUCTNAME";
ProductNameParam.SqlDbType = SqlDbType.VarChar;
ProductNameParam.Size = 25;
ProductNameParam.Direction = ParameterDirection.Input;
ProductNameParam.Value = "CHAI";
MyCommand.Parameters.Add(ProductNameParam);
MyCommand.Connection.Open();
MyReader = MyCommand.ExecuteReader(CommandBehavior.CloseConnection);
GridView1.DataSource = MyReader;
GridView1.DataBind();
MyCommand.Dispose();
MyConnection.Dispose();
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>SqlParameter example: how to use SqlParameter in asp.net</title>
</head>
<body>
<form id="form1"runat="server">
<div>
<asp:GridView ID="GridView1"runat="server">
</asp:GridView>
</div>
</form>
</body>
</html>
