How to average 3 last records?

[Tomas]

I'm creating MS Access database and I need to have in query an average of 3 last records.
How to do it?
Maybe here is some function or sql expresion?

Thanks

[MMcCarthy]

Try this ...

SELECT Avg([FieldName)
FROM (SELECT TOP 3 FieldName
FROM TableName
ORDER BY FieldName DESC);
 

[NeoPa]

Try this ...

SELECT Avg([FieldName)
FROM (SELECT TOP 3 FieldName
FROM TableName
ORDER BY FieldName DESC);
 

Other than the problem of finding the last 3 records rather than the highest 3 by fieldname, this is a perfect example of how to do it.
Tomas, you need to provide more information in the question as to how the table is structured and how the order of the records may be determined.
Please post the table MetaData in the following format :

Table Name=tblStudent
 Field; Type; IndexInfo
StudentID; Autonumber; PK
Family; String; FK
Name; String
University; String; FK
Mark; Numeric
LastAttendance; Date/Time

[Tomas]

Other than the problem of finding the last 3 records rather than the highest 3 by fieldname, this is a perfect example of how to do it.
Tomas, you need to provide more information in the question as to how the table is structured and how the order of the records may be determined.
Please post the table MetaData in the following format :

Table Name=tblStudent
 Field; Type; IndexInfo
StudentID; Autonumber; PK
Family; String; FK
Name; String
University; String; FK
Mark; Numeric
LastAttendance; Date/Time

Here is my data:
Query Name = Qry_priskaiciuota
Field; Type; Index/Info
Darbuot_ID; Numeric
Laikotarp_ID; Date/Time
Priskaiciuota_VISO; Currency

I need the Average of Priskaiciuota_VISO by 3 last Laikotarp_ID records for Darbuot_ID.

Darbuot_ID    Laikotarp_ID    Priskaiciuota_VISO
3                  2007-01-01    1.200,00 Lt
3                  2007-02-01    1.133,33 Lt
3                  2007-03-01    1.200,00 Lt
 3                  2007-04-01    1.090,91 Lt
4                  2007-01-01    818,18 Lt
4                  2007-02-01    900,00 Lt
4                  2007-03-01    900,00 Lt
 4                  2007-04-01    900,00 Lt
5                  2007-01-01    1.472,73 Lt
5                  2007-02-01    1.800,00 Lt
5                  2007-03-01    1.714,29 Lt
 5                  2007-04-01    1.800,00 Lt
6                  2007-01-01    480,00 Lt
6                  2007-02-01    600,00 Lt
6                  2007-03-01    568,00 Lt
 6                  2007-04-01    648,00 Lt
7                  2007-01-01    1.500,00 Lt
7                  2007-02-01    1.166,67 Lt
7                  2007-03-01    1.500,00 Lt
 7                  2007-04-01    1.500,00 Lt
8                  2007-01-01    3.000,00 Lt
8                  2007-02-01    3.000,00 Lt
8                  2007-03-01    3.000,00 Lt
 8                  2007-04-01    2.863,64 Lt

[NeoPa]

Try :

SELECT DISTINCT P.Darbuot_ID,
                (SELECT TOP 3 Avg(Priskaiciuota_VISO) AS AvgTop3
                 FROM Qry_priskaiciuota
                 WHERE Qry_priskaiciuota.Darbuot_ID=P.Darbuot_ID
                 ORDER BY Laikotarp_ID DESC).AvgTop3
FROM Qry_priskaiciuota AS P