如何从datetime对象获取短日期格式

Question

I am capturing the time in the text box (by using AJAX calender extender) the time in the string is 12/10/2013 , but when I assign the string to a datetime object it is converted into 12/10/2013 12:00:00 AM .

I want to use the date to filter the records in the database using the query below. Please help

string date1 = txtDate1.Text;

DateTime date = DateTime.ParseExact(txtDate1.Text, "MM/dd/yyyy", 

 System.Globalization.CultureInfo.InvariantCulture);
 string strQuery = "SELECT Story.UserName,Story.StoryId,COUNT(Likes.StoryID) AS         NumberOfOrders 
 FROM Likes LEFT JOIN Story ON Likes.StoryId=Story.StoryId and liked=" + date1 + "
 GROUP BY Story.StoryId,Story.UserName order by NumberOfOrders DESC ;";

Answer 1

It's generally not a good idea to pass dates as strings in your queries because you will most likely run into formatting issues - leave it up to the Framework you are using decide on what the best format is.

In your circumstances, you can do this by using SqlParameter s eg

DateTime date = DateTime.ParseExact(txtDate1.Text, "MM/dd/yyyy", CultureInfo.InvariantCulture);
string strQuery = "SELECT Story.UserName, Story.StoryId, COUNT(Likes.StoryID) AS NumberOfOrders 
    FROM Likes LEFT JOIN Story ON Likes.StoryId=Story.StoryId and liked=@dateTime
    GROUP BY Story.StoryId,Story.UserName order by NumberOfOrders DESC";

using (SqlConnection connection = new SqlConnection("..."))
{
    using (SqlCommand cmd = new SqlCommand(strQuery, connection))
    {
        cmd.Parameters.AddWithValue("@dateTime", date);
        connection.Open();
        SqlDataReader reader = cmd.ExecuteReader();
        ...
    }
}

Another important reason to use parameters when writing raw SQL is to ensure your user input is correctly sanatized and safe to pass to the DB. Failure to do this can leave you open to various exploitations such as SQL Injection .

Answer 2

Instead of DateTime object you can use Date object.

DateTime is an integer interpreted to represent both parts of DateTime (ie: date and time). You will always have both date and time in DateTime.

ex:

   DateTime.Now.ToString("MM/dd/yyyy");