Question

What is the formatting difference between:

DateTime datetimenow = DateTime.Now.ToLocalTime();

and

long ticks = 634687637580000000;
DateTime createdTimestamp = new DateTime(ticks).ToLocalTime();

Which causes SQL Server CE to throw error

There was an error in a part of the date format. [ Expression (if
known) = ]

I am attempting to insert two timestamps into a SQL Server CE database. The current date time and a date time from the past. The current date and time (now) can be inserted into both target fields in the table, however when I use the createdTimestamp the error above is thrown.

The format when I review the locals in debug are exactly the same between the two.

The target fields are both of datetime data type.

Why might this error be thrown?

Edit:

I’ve just found it appears to only affect timestamps in the past. Now and future timestamps work fine.

Edit: adding code for SQL insertion.

Query is built dynamically by my own SQL Server CE class.

{INSERT timeline (TweetID,Author,TimestampOfTweet,TimestampOfCollected,TweetText) VALUES ('185941815562739713','twitterapi','15/12/2011 13:52:39','01/04/2012 15:58:58','TweetDeck access - Update : This issue has been resolved. http://t.co/2yub0tYL')}

Execution Code:

//Take built statement and apply to command text
cmd.CommandText = buildSqlStatement.ToString();

//execute insert
try
{
   cmd.Connection = sqlConn;
   sqlConn.Open();
   int rows = cmd.ExecuteNonQuery();
   string results = Convert.ToString(rows);
   return results;
}
catch(Exception ex)
{
   return ex.Message;
}
finally
{
   sqlConn.Close();
}

Answer 1

Never include values directly in your SQL – always use parameterized SQL instead.

Benefits:

• Clean separation of “code” (the SQL) from data (the values)
• Protection against SQL injection attacks
• Avoids error-prone conversions such as in this question.