how to set an event to be take place daily once

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C#

Windows

forms

Hi, I want to set an action (sending message event) to take place daily once. I wrote the code for sending message in the main Form. So when user opens the application, every time the message will be sent. But I need it to happen only once in a day so the user can login everytime and message is sent only once.

Please provide me the solution and code if possible thanks in advance.

I tried following code but it doesnt work properly

try
{
    // here i try to retrieve date =date.today  from sql table;


                con.Open();
                cmd.CommandText = "select Login_Date from LoginObserver where        Login_Date =" + System.DateTime.Today;
                cmd.ExecuteNonQuery();
                con.Close();
}
// if error enter into the catch block
catch
{

/* this is my code for sending ..but i have not put entire code
   /*code for sending message*/
    sm.sendSMS("number", messagetext);
    
    insert into table where date = datetime.now;
                      con.Open();
                      cmd.CommandText = "Insert Into LoginObserver values('" + 1 + "','" + System.DateTime.Today + "')";
                      cmd.ExecuteScalar();
                      con.Close();

}

But the above code not working. Control flow is not entering the catch block.

Please provide me a solution and code.

Thanks in advance