DB2 SQL Query to group by week - sql

Question

I am writing an ASP.NET web form page using VB.Net. I am writing code to use on a line graph, but I can't seem to get my query to group by week. Here is my query:
SELECT F42119LA.SDMCU || '-' || F42119LA.SDLNTY AS BranchCode,
AVG(F42119la.SDIVD-F42119LA.SDDRQJ) AS Days,
WEEK(SDTRDJ) AS Day
FROM KAI400.KAIPRDDTA.EXCHBYDATE EXCHBYDATE,
KAI400.KAIPRDDTA.F42119L14 F42119LA
WHERE F42119LA.SDBCRC = EXCHBYDATE.CXCRCD
AND EXCHBYDATE.EXCHDATE = F42119LA.SDTRDJ
AND F42119LA.SDTRDJ>='118006'
AND F42119LA.SDTRDJ<='118096'
AND F42119LA.SDNXTR<>'999'
AND SDIVD <> 0
AND SDDRQJ <> 0
AND F42119LA.SDAEXP <> 0
AND EXCHBYDATE.CXCRDC='USD'
AND F42119LA.SDLNTY IN ('S','W')
AND (SDMCU LIKE '%100' OR SDMCU LIKE '%150')
GROUP BY SDMCU,
SDLNTY,
SDIVD,
F42119LA.SDMCU || '-' || F42119LA.SDLNTY,
WEEK(SDTRDJ)
ORDER BY SDIVD,
SDMCU,
SDLNTY
and this is the code the sql string runs through:
Public Shared Function GetMyDataTableString(SqlString As String, Optional IncDb As Integer = 0) As DataTable
Dim MyConn As OleDbConnection = GetMyConn(IncDb)
Dim DbCmd As New OleDbCommand(SqlString, MyConn)
Dim ReturnDataTable As New DataTable
Try
If Not MyConn.State = ConnectionState.Open Then
MyConn.Open()
End If
Dim Reader As OleDbDataReader = DbCmd.ExecuteReader(CommandBehavior.CloseConnection)
Using Reader
ReturnDataTable.Load(Reader)
End Using
Catch ex As Exception
LogSqlErrors(SqlString, "GetMyDataTableString " & ex.Message.ToString(), IncDb)
If HttpContext.Current.Session("SITEADMIN") = "True" Then
HttpContext.Current.Response.Write("<b>OleFun.GetMyDataTableString, datatable failed</b>---<br />" & ex.ToString)
End If
Finally 'Happens regardless of failing or succeeding
MyConn.Close()
End Try
Return ReturnDataTable
End Function
Whenever I use WEEK(), it gives me this error:
Value in date, time, or timestamp string not valid
ONDATE is a date field in format MM/DD/YYYY. Does anyone know another way to group by week or what might can be giving me this error? Thanks in advance for your responses.

Answer 1

-- date part takes the part of the date as first paramater:
-- you have:
DATEPART(SDTRDJ, wk)
-- needs to be:
DATEPART(wk, SDTRDJ)

Answer 2

DATEPART() might be a function in SQL Server, but it not a function in Db2. You could use WEEK() or WEEK_ISO() which are Db2 functions. https://www.ibm.com/support/knowledgecenter/en/SSEPGG_11.1.0/com.ibm.db2.luw.sql.ref.doc/doc/r0005481.html
You could also use EXTRACT if you are on a recent version of Db2 LUW
https://www.ibm.com/support/knowledgecenter/en/SSEPGG_11.1.0/com.ibm.db2.luw.sql.ref.doc/doc/r0053629.html
db2 "values extract(WEEK FROM current date)"
1
-----------
14
1 record(s) selected.
BTW you don't need to group by the concatenation of F42119LA.SDMCU || '-' || F42119LA.SDLNTY, you can group by those columns individually, and only concat in the SELECT.

Answer 3

In DB2, you can group days in same week using following methods:
DATE_PART('WEEK', dateColumn) -> week starts at Saturday
WEEK(dateColumn) -> week starts at Sunday
WEEK_ISO(dateColumn) -> week starts at Monday
DAYS(dateColumn) / 7 -> week starts at Sunday
Notes:
I believe that they work with columns of type DATE as will as TIMESTAMP.
"DAYS(dateColumn) / 7" doesn't get you week number, however it is helpful in grouping by week.
Kindly check your week start day as they differ in their results as following: