Why does "WHERE (Time_Stamp >= TDateTime-variable)" ignore fractional seconds? - sql

Question

Using Delphi 6 and Microsoft SQL Server 2000.
I need to extract records where a TDateTime Field is > a passed TDateTime, "FromDate".
It fails as if the fractional part of the seconds of the passed TDateTime are always zero.
Debug printouts confirm that the fractions are there.
The WHERE part ignores the fraction part of :Fdate.
Assume the following 3 records:
Record 1: Time_Stamp is 1.2
Record 2: Time_Stamp is 1.4
Record 3: Time_Stamp is 1.6
The value 1.3 is then sent to the Query in :Fdate.
The resulting dataset returns ALL 3 records.
I expected only records 2 and 3 since 1.3 > 1.2
The 'Time_Stamp' field in database is a SQL 'datetime' field.
Everything works perfectly for integer seconds,
i.e. one record per second, or less often, when the decimal fraction is unimportant.
Can anyone point out where my error is?
The SQL statement is generated by code (shown below) as follows:
SELECT TOP 6 * FROM T_TransactionLog
INNER JOIN T_LookUp_TransTypes
ON T_TransactionLog.TransType = T_LookUp_TransTypes.TransType
WHERE (Time_Stamp >= :Fdate)
AND T_TransactionLog.TransType IN (
3,
4,
5
)
AND LockerNo < 60001
ORDER BY Time_Stamp ASC
The code is as follows:
Query.Connection := Sys_DB_Form.ADOConnection;
DataSource.DataSet := Query;
Query.SQL.Add('SELECT TOP ' + IntToStr(cNoTransactions) + ' * FROM
T_TransactionLog');
Query.SQL.Add('INNER JOIN T_LookUp_TransTypes');
Query.SQL.Add('ON T_TransactionLog.TransType =
T_LookUp_TransTypes.TransType');
Query.SQL.Add('WHERE (Time_Stamp ' + S_Condition + ' :Fdate)');
Query.SQL.Add('AND T_TransactionLog.TransType IN (');
Query.SQL.Add(IntToStr(ord(Apl_TrLog.ttEA)) + ',');
Query.SQL.Add(IntToStr(ord(Apl_TrLog.ttMO)) + ',');
Query.SQL.Add(IntToStr(ord(Apl_TrLog.ttMC)));
Query.SQL.Add(')');
Query.SQL.Add('AND LockerNo < ' +
IntToStr(Apl_Config.cLNoOfFirstgate));
if Locker <> 0 then
begin
Query.SQL.Add('AND LockerNo = ' + IntToStr(Locker));
end;
Query.SQL.Add(S_OrderBy);
Query.Parameters.FindParam('Fdate').Value := FromDate; // <<< Fail????
Query.SQL.SaveToFile(GetApplicationDataPath + 'Sql.txt');
try
Query.Open;
except
ShowMessage('Query open fail on ME Show Transaction log');
end;

Answer 1

Please chech the accuracy note for SQL Server datetime and time data types on MSDN
It is written that:
Accuracy Rounded to increments of .000, .003, or .007 seconds
This means
23:59:59.997
is OK
But
23:59:59.998
will be rounded to 23:59:59.997
And
23:59:59.999
will be rounded to 00:00:00 for the next day