Compare date from textbox with date in database in ASP.NET using C#

Question

I am trying to compare a date I enter in a textbox in a DD.MM.YYYY format and I get an error.

string txt = "select count(*) from cont where Data_deschiderii < " + Convert.ToDateTime(TextBox1.Text).ToString("DD.MM.YYYY");

SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
conn.Open();

SqlCommand cmd = new SqlCommand(txt, conn);
int x = Convert.ToInt32(cmd.ExecuteScalar().ToString());
Response.Write(x);

How could I do it? I couldn't find ANYTHING on the internet

Answer 1

The best approach is to start using prepared, parameterized queries. They ensure that comparisons are done correctly, and they prevent the possibility of SQL injection attacks.

Your code would be rewritten like this:

string txt = "select count(*) from cont where Data_deschiderii < @compareDate;"; 
SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
conn.Open();
SqlCommand cmd = new SqlCommand(txt, conn);
cmd.Parameters.Add("@compareDate", SqlDbType.Date);
cmd.Parameters["@compareDate"].Value = TextBox1.Text;
int x = Convert.ToInt32(cmd.ExecuteScalar().ToString());
Response.Write(x);

That is, I am assuming that your database field Data_deschiderii is of a date form of datatype.

Answer 2

You need to convert the date time to something SQL understands.

var formattedDate = Convert.ToDateTime(TextBox1.Text).ToString("yyyy-MM-dd HH:mm:ss");

And then use formattedDate in your query

Answer 3

You should convert the datetime in timespan and then compare that timespan in seconds. In SQL you could convert the same using DateDiff function.

Answer 4

Try this.

try
{
  DateTime Date1= Convert.ToDateTime(TextBox1.Text).ToString("yyyy-MM-dd HH:mm:ss");
  DateTime Date2 = Convert.ToDateTime(TextBox2.Text).ToString("yyyy-MM-dd HH:mm:ss");
  if (Date1 > Date2) 
  {
    Your Code...
  }
}
catch (Exception ex)
{
    MessageBox.Show(ex.Message);
}