Data type mismatch in criteria expression | Access, OleDb, C#

Question

I read/update data from MS Access using C#. My code is:

public static void UpdateLastLogin(int userid, DateTime logintime) ///logintime = DateTime.Now
{
             


        

Answer 1

Firstly, no your SQL statement should be:

"UPDATE Customers SET LastLogin=@LastLogin"

Secondly, the reason you are receiving the date mismatch error will probably be your passing '?' as your date time into the LastLogin field instead of the actual logintime parameter.

Answer 2

Try setting the "DBTYPE" property of the parameter to identify it as a date, datetime or datetime2 as appropriate...

prms[0].DbType = DbType.DateTime;

There are 7 signatures to the new OleDbParameter() call, so you may change the signature instance, or just do explicitly as I sampled above since you only had 1 parameter in this case.

Answer 3

maybe try

DateTime.Now.ToShortDateString() + ' ' + DateTime.Now.ToShortTimeString()

instead, pass it as String (and maybe enclose with # then)

Answer 4

I solved this using the following code

OleDbCommand cmd = new OleDbCommand(qry, cnn);
cmd.Parameters.Add("datenow", OleDbType.Date);
cmd.Parameters["datenow"].Value = DateTime.Now;

Answer 5

Should it not be

"UPDATE Customers SET LastLogin='@LastLogin'"

And @LastLogin should be

logintime.ToString("yyyy-MM-dd hh:mm:ss")

edit Could you not just inline the whole thing?

"UPDATE Customers SET LastLogin='" + logintime.ToString("yyyy-MM-dd hh:mm:ss") + "'"

Answer 6

There is a known issue with OleDb and dates. Try doing something like:

OleDbParameter p = parameter as OleDbParameter;
if (null == p)
  parameter.DbType = DbType.DateTime;
else
  p.OleDbType = OleDbType.Date;

Or use explicit format string:

value.ToString("yyyy-MM-dd hh:mm:ss")