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Best way to Compare DateTime to trigger code

What is the best way to compare two DateTime in a specific format and trigger code if DateTime has passed.
My DateTime is formatted as 4/26/2017 10:00:00 AM
DateTime currentDateTime = DateTime.Now;
DateTime eventDateTime = DateTime.Parse("4/26/2017 10:00:00 AM");
int result = DateTime.Compare(currentDateTime, eventDateTime);
if (result < 0)
Response.Write( "is earlier than Do Nothing");
else if (result == 0)
Response.Write("is the same time as: Do Nothing");
else
Response.Write("Time is greater, Trigger Action ");
Is the above code fine for comparison or we can improve it.

For my opinion, the method you suggested is the most efficiant and accepted way to compare 2 DateTime variables in C#, considering you need to take action if the 2 dates are also equal.
Side note:
If you only needed to compare the 2 DateTime without the equal condition, you could just write:
if (currentDateTime < eventDateTime)
Response.Write("is earlier than Do Nothing");
else
Response.Write("Time is greater, Trigger Action");
which is a bit cleaner and more efficiant.

To compare Dates, your method is efficient one because according to MSDN
The CompareTo method compares the Ticks property of the current instance and value but ignores their Kind property. Before comparing DateTime objects, make sure that the objects represent times in the same time zone.
So as it does compare Ticks of two instances of DateTime, so it is the efficient method for comparison.
As a side note, if you want to find interval between DateTime Instances then you can use DateTime.Subtraction it will give TimeSpan of both DateTime instances. So you can find total difference in their minutes, hours, days, seconds, milliseconds by using TimeSpan properties.
DateTime date1 = new DateTime(2010, 1, 1, 8, 0, 15);
DateTime dateNow = DateTime.Now;
TimeSpan interval = dateNow.Subtract(date1);
double totalHours= interval.TotalHours;
double totalMinutes = interval.TotalMinutes;
double totalSeconds= interval.TotalSeconds;
double totalMilliseconds= interval.TotalMilliseconds;

You can use nested if else statement as below:
if (currentDateTime < eventDateTime)
Response.Write("is earlier than Do Nothing");
else if(currentDateTime > eventDateTime)
Response.Write("time is greater, Trigger Action");
else
Response.Write("is the same time as: Do Nothing");

DateTime.MinValue and SqlDateTime overflow

I don't want to validate txtBirthDate so I want to pass DateTime.MinValue in database.
My code:
if (txtBirthDate.Text == string.Empty)
objinfo.BirthDate = DateTime.MinValue;
else
objinfo.BirthDate = DateTime.Parse(txtBirthDate.Text);
DateTime.MinValue return Date = {1/1/0001 12:00:00 AM}
I got a SQL Error:
SqlDateTime overflow. Must be between 1/1/1753 12:00:00 AM and 12/31/9999 11:59:59 PM.
I under stand it but I don't understand why DateTime.MinValue return invalid date time which is unable to insert in database.How to handle this type of situation?

Very simple avoid using DateTime.MinValue use System.Data.SqlTypes.SqlDateTime.MinValue instead.

Basically, don't use DateTime.MinValue to represent a missing value. You can't use DateTime.MinValue in a SQL Server DateTime field, as SQL Server has a minimum value of the start of 1753.
Instead, make your BirthDate property a Nullable<DateTime> (aka DateTime?), and set it to null when you don't have a value. Also make sure your database field is nullable. Then you just need to make sure that that null ends up as a NULL value in the database. Exactly how you do that will depend on your data access, which you haven't told us anything about.

Well... its quite simple to get a SQL min date
DateTime sqlMinDateAsNetDateTime = System.Data.SqlTypes.SqlDateTime.MinValue.Value;

Although it is an old question, another solution is to use datetime2 for the database column.
MSDN Link

Here is what you can do. Though there are lot many ways to achieve it.
DateTime? d = null;
if (txtBirthDate.Text == string.Empty)
objinfo.BirthDate = d;
else
objinfo.BirthDate = DateTime.Parse(txtBirthDate.Text);
Note: This will work only if your database datetime column is Allow Null. Else you can define a standard minimum value for DateTime d.

I am using this function to tryparse
public static bool TryParseSqlDateTime(string someval, DateTimeFormatInfo dateTimeFormats, out DateTime tryDate)
{
bool valid = false;
tryDate = (DateTime)System.Data.SqlTypes.SqlDateTime.MinValue;
System.Data.SqlTypes.SqlDateTime sdt;
if (DateTime.TryParse(someval, dateTimeFormats, DateTimeStyles.None, out tryDate))
{
try
{
sdt = new System.Data.SqlTypes.SqlDateTime(tryDate);
valid = true;
}
catch (System.Data.SqlTypes.SqlTypeException ex)
{
}
}
return valid;
}

From MSDN:
Date and time data from January 1, 1753, to December 31, 9999, with an
accuracy of one three-hundredth second, or 3.33 milliseconds. Values
are rounded to increments of .000, .003, or .007 milliseconds. Stored
as two 4-byte integers. The first 4 bytes store the number of days
before or after the base date, January 1, 1900. The base date is the
system's reference date. Values for datetime earlier than January 1,
1753, are not permitted. The other 4 bytes store the time of day
represented as the number of milliseconds after midnight. Seconds have
a valid range of 0–59.
SQL uses a different system than C# for DateTime values.
You can use your MinValue as a sentinel value - and if it is MinValue - pass null into your object (and store the date as nullable in the DB).
if(date == dateTime.Minvalue)
objinfo.BirthDate = null;

Simply put, don't use DateTime.MinVaue as a default value.
There are a couple of different MinValues out there, depending which environment you are in.
I once had a project, where I was implementing a Windows CE project, I was using the Framework's DateTime.MinValue (year 0001), the database MinValue (1753) and a UI control DateTimePicker (i think it was 1970). So there were at least 3 different MinValues that were leading to strange behavior and unexpected results. (And I believe that there was even a fourth (!) version, I just do not recall where it came from.).
Use a nullable database field and change your value into a Nullable<DateTime> instead. Where there is no valid value in your code, there should not be a value in the database as well. :-)

If you use DATETIME2 you may find you have to pass the parameter in specifically as DATETIME2, otherwise it may helpfully convert it to DATETIME and have the same issue.
command.Parameters.Add("#FirstRegistration",SqlDbType.DateTime2).Value = installation.FirstRegistration;

use extensions
public static class DateTimeExtensions
{
public static DateTime MinValue(this DateTime sqlDateTime)
{
return new DateTime(1900, 01, 01, 00, 00, 00);
}
}
DateTime date = DateTime.Now;
Console.WriteLine("Minvalue is {0} ", date.MinValue().ToShortDateString());

Exact c# result of sql datediff

I'm trying to get the number of days (calculated byu datediff) in sql and the number of days in c# (calculated by DateTime.now.Substract) to be the same, but they return different results....
//returns 0
int reso = DateTime.Now.Subtract(expirationDate).Days;
vs
//returns 1
dateDiff(dd,getDate(),ExpirationDate)
In both cases, ExpirationDate is '10/1/2011 00:00:00', and the code and the DB are sitting on the same server. I want the return int to be the same. I suspect I'm missing something stupid... ideas??

dateDiff(dd,getDate(),ExpirationDate) Is doing a days comparison. DateTime.Now.Subtract(expirationDate).Days is doing a date and time
For example
SELECT dateDiff(dd,'10/1/2011 23:59:00' , '10/2/2011') returns one day even when only one minute apart.
If you want the same in C# you need to remove the time component
e.g.
DateTime dt1 = new DateTime(2011,10,1, 23,59,0);
DateTime dt2 = new DateTime(2011,10,2, 0,0,0);
Console.WriteLine((int) dt2.Subtract(dt1.Subtract(dt1.TimeOfDay)));
So in your case it would be something like
DateTime CurrentDate = DateTime.Now;
int reso = CurrentDate.Subtract(CurrentDate.TimeOfDay).Subtract(DateTime.expirationDate).Days;
I haven't tested it but I would not do
DateTime.Now.Subtract(DateTime.Now.Subtract.TimeOfDay)
Because the second call to Now wouldn't be guaranteeing to be the same as first call to Now
In any case Stealth Rabbi's answer seems more elegant anyway since you're looking for a TimeSpan not a DateTime

10/1/2011 is less than 1 day away from DateTime.Now. Since you're getting back a TimeSpan and then applying Days to it, you're getting back a TimeSpan that is < 1 day. So it'll return 0 Days.
Instead, just use the Date component of those DateTimes and it'll correctly report the number of days apart - like this:
DateTime now = DateTime.Now;
DateTime tomorrow = new DateTime(2011, 10, 1);
var val = (tomorrow.Date - now.Date).Days;
This will yield you 1 day.

I'm assuming you want the number of Total days, not the number of days from the largest previous unit. You'd want to use the TotalDays property. Also, you may find it easier to use the minus operator to do a subtraction
DateTime d1 = DateTime.Now;
DateTime d2 = new DateTime(2009, 1, 2);
TimeSpan difference = d1 - d2;
Console.WriteLine(difference.TotalDays); // Outputs (today):1001.46817997424

Comparing DateTime objects

Goal - find out which DateTime is more recent.
Can I figure this out with this code:
DateTime dt1 = new DateTime(...); //let's say it was created on 1/1/2000
DateTime dt2 = new DateTime(...); //let's say it was create on 1/1/2011
if (dt2.ToBinary() > dt1.ToBinary()) {
print dt2 is newer than dt1 }
Can I simply convert the DateTime objects to binary, then presume that the larger one is more recent?
Thanks,
Kevin

if (dt2 > dt1) {
print dt2 is newer than dt1 }
should be enough as DateTime overloads the comparison operators.

You can usually do better than that:
if (dt2 > dt1)
The tricky bit is taking time zones into consideration... you can potentially use
if (dt2.ToUniversalTime() > dt1.ToUniversalTime())
but only if you know that any "local" times really are local in the system's time zone.
Dates and times in .NET are a bit of a mess :(

No, you can't. ToBinary() returns an internal format that also stores time zone info.
Instead, you can compare the DateTimes directly:
if (dt2 > dt1)
DateTime overloads the comparison operators.
You could compare the Ticks property, but you shouldn't bother.

You can use Datetime.Compare
int iDiff = DateTime.Compare(new DateTime(2011, 02, 28), new DateTime(2011, 01, 30));
-1 = The Fisrt Date is Less than the Second
0 = The First Date is equal than the Second
1 = The First Date is Greater than the Second

DateTime objects are comparable themselves, so
if (dt1>dt2)
Console.WriteLine('dt1 is newer');
else if (dt1>dt2)
Console.WriteLine('dt2 is newer');
else // they are equal
Console.WriteLine('dt1 and dt2 are the same');
will work too.
In addition DateTime implements the IComparable<DateTime> interface, so you can do:
int result = dt1.CompareTo(dt2);
if (result > 0)
Console.WriteLine('dt1 is newer');
else if (result < 0)
Console.WriteLine('dt2 is newer');
else // result = 0
Console.WriteLine('dt1 and dt2 are the same');
EDIT: This ignores time zones, local times, etc...

Parsing times above 24 hours in C#

Suppose a time stamp (just time or date and time) where the time can roll over to the next day:
00:00:00 <- midnight
01:00:00 <- 1 AM
23:00:00 <- 11 PM
24:00:00 <- midnight, day + 1
25:00:00 <- 1 AM, day + 1
What would be a way to parse it easily into a C# DateTime that would perform the carry-over to the next day? In other words, "01:00:00" would become "0001-01-01 01:00:00" and "25:00:00" would become "0001-01-02 01:00:00".
EDIT:
I should mention that this fails miserably (i.e FormatException):
DateTime.ParseExact("0001-01-01 25:00:00", "yyyy-MM-dd HH:mm:ss", CultureInfo.InvariantCulture);

Since you're trying to represent a period of time from an arbitrary point, rather than as a specific date, perhaps you would be better off using the System.TimeSpan class? This allows you to set values of more than 24 hours in the constructor, and can be used with DateTime objects like this:
System.TimeSpan timestamp = new System.TimeSpan(25, 0, 0);
System.DateTime parsedDateTime = new DateTime(0, 0, 0);
parsedDateTime = parsedDateTime.Add(timestamp);
Console.WriteLine(parsedDateTime.ToString("yyyy-MM-dd HH:mm:ss")); //Output as "0001-01-02 01:00:00"
NOTE: Code is untested.
EDIT: In terms of parsing the strings, I can't think of any basic .NET objects that parse strings with values greater than 23 for the hour (since 25 is an invalid hour of the day), but assuming that the format is consistent, you could create a very simple string parsing routine (or even a regular expression) to read the values individually, and load the constructor manually.

If you have an existing DateTime value you can add to, you can always use a TimeSpan:
string dt = "25:00:00";
int hours = int.Parse(dt.Split(':')[0]);
TimeSpan ts = TimeSpan.FromHours(hours);
TimeSpan.Parse() doesn't work directly in this case because it complains (fair enough!) about the 25 in the hour notation.

If you want to code it out... this should be a starting point:
string dateString = "0001-01-01 25:00:00";
string[] parts = dateString.Split(' '); //now have '0001-01-01' and '25:00:00'
string datePart = parts[0]; // '0001-01-01'
string[] timeParts = parts[1].Split(':'); //now have '25', '00', and '00
DateTime initialDate = DateTime.ParseExact(datePart, "yyyy-MM-dd", CultureInfo.InvariantCulture);//use the date as a starting point
//use the add methods to get your desired datetime
int hours = int.Parse(timeParts[0]);
int minutes = int.Parse(timeParts[1]);
int seconds = int.Parse(timeParts[2]);
DateTime resultDate = initialDate.AddHours(hours)
.AddMinutes(minutes)
.AddSeconds(seconds);
Of course, it makes assumptions that the input is formatted properly and is parsable, etc..
In addition, you could definitely use timespan instead of the individual add methods for hour, minute, second as some other answers are..

In case nobody points out an out-of-the-box answer, here is a neat ActionScript class I wrote to parse time inputs (human input)...
https://github.com/appcove/AppStruct/blob/master/Flex/AppStruct/src/AppStruct/TimeInput.as
It would be very simple to port this to C#, and you could tweak the 24 hour logic to result in #days, #hours, #minutes.
Good luck!

You are specifying an invalid date. So not only can you not parse it, you cannot store it!
How about a nice TimeSpan object instead? (It also has a Parse() method.)
Alternatively, use a sscanf()-type function like the one at http://www.blackbeltcoder.com/Articles/strings/a-sscanf-replacement-for-net to extract each number separate. (Best if you have no control over the string format being read.)