The variable 'sql' is assigned but its value is never used

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
 
public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        //Default SQL statement which will be executed when no search conditions were entered
        String sql = "SELECT tblSecurity.Username, tblSecurity.First_Name, tblSecurity.Last_Name, tblSecurity.Company_number FROM tblSecurity";
        //Connection string - @@DBName will be replaced by the server name selected from the
        //Environment dropdown
        String connString = "DATA SOURCE = Labsdirvg600;Initial Catalog=TimeEntry;User ID=Labswirvg600;Password=Kling0n1";
        //A boolean field which is used to add a WHERE clause to the SQL statement
        //Boolean whereClauseAdded = false;
 
        //Connection string is formed here. cboEnvironment.SelectedItem.Value will return
        //the selected environment.
        //connString = connString.Replace("@@DBName", cboEnvironment.SelectedItem.Value);
    }
 
    protected void btnSubmit_Click(object sender, EventArgs e)
    {
        if (query.Checked)
            sql = "SELECT * from tblSecurity where Username Like '%sm'";
        if (query.Checked)
 
            sql = "SELECT * from tblSecurity where Username Like '%jo'";
 
 
        //Set the connection string of the SQLDataSource here
        dsToolkit.ConnectionString = connString;
 
        //Atleast one search criteria must be entered by the user if a WHERE clause needs to be
        //added
 
        //Now, the dynamically created SQL statement needs to be assigned to the SQL Data source
        dsToolkit.SelectCommand = sql;
 
        //Finally, refresh the Grid, which will cause the data source to execute the above created
        //SQL and show the results in the grid
        grdPayroll.DataBind();
    }
 
}

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