.NET DateTime 到 SqlDateTime 的转换

Question

在将 .NET DateTime (when is default(DateTime)) 转换为 SqlDateTime 时，我应该总是检查 .NET 日期是否在 SqlDateTime.MinValue 和 SqlDateTime.MaxValue [或] 之间有没有好的方法可以做到这一点。

Answer 1

Is it possible that the date could actually be outside that range? Does it come from user input? If the answer to either of these questions is yes, then you should always check - otherwise you're leaving your application prone to error.

You can format your date for inclusion in an SQL statement rather easily:

var sqlFormattedDate = myDateTime.Date.ToString("yyyy-MM-dd HH:mm:ss");

Answer 2

If you are checking for DBNULL, converting a SQL Datetime to a .NET DateTime should not be a problem. However, you can run into problems converting a .NET DateTime to a valid SQL DateTime.

SQL Server does not recognize dates prior to 1/1/1753. Thats the year England adopted the Gregorian Calendar. Usually checking for DateTime.MinValue is sufficient, but if you suspect that the data could have years before the 18th century, you need to make another check or use a different data type. (I often wonder what Museums use in their databases)

Checking for max date is not really necessary, SQL Server and .NET DateTime both have a max date of 12/31/9999 It may be a valid business rule but it won't cause a problem.

Answer 3

Also please remember resolutions [quantum of time] are different.

http://msdn.microsoft.com/en-us/library/system.data.sqltypes.sqldatetime.aspx

SQL one is 3.33 ms and .net one is 100 ns.

Answer 4

on my quest to do this with entitie, i stumbled over here, just hitting back to post what i've found out...

when using EF4, "a sql's" datetime column can be filled from .NET's DateTime using BitConverter.

EntitieObj.thetime = BitConverter.GetBytes(DateTime.Now.ToBinary());

also Fakrudeen's link brought me further... thank you.

Answer 5

- 仅比较日期部分，您可以执行以下操作：

var result = db.query($"SELECT * FROM table WHERE date >= '{fromDate.ToString("yyyy-MM-dd")}' and date <= '{toDate.ToString("yyyy-MM-dd"}'");

Answer 6

var sqlCommand = new SqlCommand("SELECT * FROM mytable WHERE start_time >= @StartTime");
sqlCommand.Parameters.Add("@StartTime", SqlDbType.DateTime);
sqlCommand.Parameters("@StartTime").Value = MyDateObj;