Fetching table's data row by row [duplicate] - sql

Question

I need a code to loop through all the records in a table so I can extract some data. In addition to this, is it also possible to loop through filtered records and, again, extract data? Thanks!

Answer 1

You should be able to do this with a pretty standard DAO recordset loop. You can see some examples at the following links:
http://msdn.microsoft.com/en-us/library/bb243789%28v=office.12%29.aspx
http://www.granite.ab.ca/access/email/recordsetloop.htm
My own standard loop looks something like this:
Dim rs As DAO.Recordset
Set rs = CurrentDb.OpenRecordset("SELECT * FROM Contacts")
'Check to see if the recordset actually contains rows
If Not (rs.EOF And rs.BOF) Then
rs.MoveFirst 'Unnecessary in this case, but still a good habit
Do Until rs.EOF = True
'Perform an edit
rs.Edit
rs!VendorYN = True
rs("VendorYN") = True 'The other way to refer to a field
rs.Update
'Save contact name into a variable
sContactName = rs!FirstName & " " & rs!LastName
'Move to the next record. Don't ever forget to do this.
rs.MoveNext
Loop
Else
MsgBox "There are no records in the recordset."
End If
MsgBox "Finished looping through records."
rs.Close 'Close the recordset
Set rs = Nothing 'Clean up

Answer 2

In "References", import DAO 3.6 object reference.
private sub showTableData
dim db as dao.database
dim rs as dao.recordset
set db = currentDb
set rs = db.OpenRecordSet("myTable") 'myTable is a MS-Access table created previously
'populate the table
rs.movelast
rs.movefirst
do while not rs.EOF
debug.print(rs!myField) 'myField is a field name in table myTable
rs.movenext 'press Ctrl+G to see debuG window beneath
loop
msgbox("End of Table")
end sub
You can interate data objects like queries and filtered tables in different ways:
Trhough query:
private sub showQueryData
dim db as dao.database
dim rs as dao.recordset
dim sqlStr as string
sqlStr = "SELECT * FROM customers as c WHERE c.country='Brazil'"
set db = currentDb
set rs = db.openRecordset(sqlStr)
rs.movefirst
do while not rs.EOF
debug.print("cust ID: " & rs!id & " cust name: " & rs!name)
rs.movenext
loop
msgbox("End of customers from Brazil")
end sub
You should also look for "Filter" property of the recordset object to filter only the desired records and then interact with them in the same way (see VB6 Help in MS-Access code window), or create a "QueryDef" object to run a query and use it as a recordset too (a little bit more tricky). Tell me if you want another aproach.
I hope I've helped.

Answer 3

Found a good code with comments explaining each statement.
Code found at - accessallinone
Sub DAOLooping()
On Error GoTo ErrorHandler
Dim strSQL As String
Dim rs As DAO.Recordset
strSQL = "tblTeachers"
'For the purposes of this post, we are simply going to make
'strSQL equal to tblTeachers.
'You could use a full SELECT statement such as:
'SELECT * FROM tblTeachers (this would produce the same result in fact).
'You could also add a Where clause to filter which records are returned:
'SELECT * FROM tblTeachers Where ZIPPostal = '98052'
' (this would return 5 records)
Set rs = CurrentDb.OpenRecordset(strSQL)
'This line of code instantiates the recordset object!!!
'In English, this means that we have opened up a recordset
'and can access its values using the rs variable.
With rs
If Not .BOF And Not .EOF Then
'We don’t know if the recordset has any records,
'so we use this line of code to check. If there are no records
'we won’t execute any code in the if..end if statement.
.MoveLast
.MoveFirst
'It is not necessary to move to the last record and then back
'to the first one but it is good practice to do so.
While (Not .EOF)
'With this code, we are using a while loop to loop
'through the records. If we reach the end of the recordset, .EOF
'will return true and we will exit the while loop.
Debug.Print rs.Fields("teacherID") & " " & rs.Fields("FirstName")
'prints info from fields to the immediate window
.MoveNext
'We need to ensure that we use .MoveNext,
'otherwise we will be stuck in a loop forever…
'(or at least until you press CTRL+Break)
Wend
End If
.close
'Make sure you close the recordset...
End With
ExitSub:
Set rs = Nothing
'..and set it to nothing
Exit Sub
ErrorHandler:
Resume ExitSub
End Sub
Recordsets have two important properties when looping through data, EOF (End-Of-File) and BOF (Beginning-Of-File). Recordsets are like tables and when you loop through one, you are literally moving from record to record in sequence. As you move through the records the EOF property is set to false but after you try and go past the last record, the EOF property becomes true. This works the same in reverse for the BOF property.
These properties let us know when we have reached the limits of a recordset.