This is a super basic question but I'm trying to execute a Query that I'm building via some form values against the MS Access database the form resides in. I don't think I need to go through ADO formally, but maybe I do.
Anyway, some help would be appreciated. Sorry for being a n00b. ;)
You can use the following DAO code to query an Access DB:
Dim rs As DAO.Recordset
Dim db As Database
Set db = CurrentDb
Set rs = db.OpenRecordset("SELECT * FROM Attendance WHERE ClassID = " & ClassID)
do while not rs.EOF
'do stuff
rs.movenext
loop
rs.Close
Set rs = Nothing
In my case, ClassID is a textbox on the form.
This is what I ended up coming up with that actually works.
Dim rs As DAO.Recordset
Dim db As Database
Set db = CurrentDB
Set rs = db.OpenRecordset(SQL Statement)
While Not rs.EOF
'do stuff
Wend
rs.Close
Here just in case you wanted an ADO version:
Dim cn as new ADODB.Connection, rs as new ADODB.RecordSet
Dim sql as String
set cn = CurrentProject.Connection
sql = "my dynamic sql string"
rs.Open sql, cn ', Other options for the type of recordset to open, adoOpenStatic, etc.
While Not rs.EOF
'do things with recordset
rs.MoveNext ' Can't tell you how many times I have forgotten the MoveNext. silly.
Wend
rs.Close
cn.Close
Set rs = Nothing
Set cn = Nothing
DAO and ADO are very close in usage. You get more control with DAO and slightly better performance with ADO. In most access database applications I have come across it really doesn't make a difference. When I have seen a big difference is with linked tables. ADO often performs better.
The answers you've been given and that you seem to be accepting loop through a DAO recordset. That is generally a very inefficient method of accomplishing a text. For instance, this:
Set db = CurrentDB()
Set rs = db.OpenRecordset("[sql]")
If rs.RecordCount > 0
rs.MoveFirst
Do While Not rs.EOF
rs.Edit
rs!Field = "New Data"
rs.Update
rs.MoveNext
Loop
End If
rs.Close
Set rs = Nothing
Set db = Nothing
will be much less efficient than:
UPDATE MyTable SET Field = "New Data"
which can be run with:
CurrentDb.Execute "UPDATE MyTable SET Field = 'New Data'"
It is very seldom the case that one needs to loop through a recordset, and in most cases a SQL update is going to be orders of magnitude faster (as well as causing much shorter read/write locks to be held on the data pages).
Related
I am querying my access table using VBA and writing the query result in excel.
EOF is always true but BOF is False - even if the record count is 1 or 14 or 100. What possibly would be wrong? I can see the record count more than zero. get string value has data in it. Due to this there is no data written in the destination sheet except for Headers. The headers are coming in fine.
List of things tried but result was still same:
Added Move last and Move first command
Tried all possible combinations of Cursor location, cursor type, lock type
Tried with execute command
Tried with different MS access table
Tried early and late binding techniques
Below is my query and link below is my how my record set looks after SQL open statement.
Const MyConn = "Access DB location"
Dim con As ADODB.Connection
Dim rs As ADODB.Recordset
Set con = New ADODB.Connection
With con
.Provider = "Microsoft.ACE.OLEDB.12.0"
.Open MyConn
End With
QuerySql = "SELECT * FROM Store_Location"
Set rs = New ADODB.Recordset
rs.CursorLocation = adUseClient
rs.Open QuerySql, con, adOpenStatic, adLockReadOnly, adCmdUnknown
rs.MoveLast
rs.MoveFirst
i = 0
For i = 0 To rs.Fields.Count - 1
Sheets("Search_Temp").Cells(1, i + 1) = rs.Fields(i).Name
Next i
Range("A2").CopyFromRecordset rs
rs.Close
Set rs = Nothing
con.Close
Set con = Nothing
While debugging this is what my record set looks like:
Building on this answer to a similar question, calling getString on a Recordset object has a side-effect of moving the recordset to EOF.
You don't call getString anywhere in your code but you've added a watch on rs.getString which is visible as the last entry in the Watches window. If you have a watch on rs.getString and you have a breakpoint in the code where rs is open then that breakpoint will cause the recordset to move to EOF.
Depending on where the breakpoint occurs, this might not cause any issues (e.g. if the recordset was already at EOF) but, in this case, it is moving the recordset to EOF before you have copied the data from the recordset.
To solve this issue, remove the watch on rs.getString. It's probably a bad idea in general to have items in the Watches window cause side effects. You could also avoid the issue by not having any breakpoints where the recordset is open but removing the watch entirely is more robust.
The issue of getString moving the recordset to EOF isn't mentioned in the ADO documentation but it's easy to reproduce this effect.
It's uncommon for someone to include the entire list of watches they had set in their question but I'm not sure this question was answerable without that information
I am new to MS Access and would like to type EmployeeID in the text box 1 (text_in) and after the button is pressed the result query (one unique value e.g. employee first name taken from the table) is printed out in the text box2 (text_out).
So far have the following code:
Private Sub btn_get_data_Click()
Dim db As DAO.Database
Dim rs As DAO.Recordset
'declaration of database on recordset objects
Dim strSQL As String
Dim a As String
a = text_in.Value
Set db = CurrentDb
Set rs = db.OpenRecordset("Employee")
strSQL = "SELECT Employee.FirstName FROM Employee WHERE Employee.EmployeeId=" & a
Set db = Nothing
Set rs = Nothing
End Sub
I have tried searching for a solution in many places but I cannot understand the structure that is used in MS access VBA to implement query from regular SQL language.
Guys, thank you very much! It took me one more hour to sucessfully implement both solutions into my database file. As I wrote I am completely new to Ms-access I am learning using some tutorials but my level is still low. Thank you very much once again.
Private Sub btn_get_data_Click()
on error goto errorCatch
Dim db As DAO.Database
Dim rs As DAO.Recordset
Dim strSQL As String
Set db = CurrentDb
strSQL = "SELECT Employee.FirstName FROM Employee WHERE Employee.EmployeeId=" & Me.text_in.Value & ";"
Set rs = db.OpenRecordset(strSql, DbOpenDynaset)
If rs.RecordCount > 0 Then
debug.print; rs!FirstName
Me.text_out.Value = rs!FirstName
End if
Cleanup:
Set db = Nothing
Set rs = Nothing
Exit Sub
errorCatch:
debug.print; err.Number
debug.print; Err.Description
GoTo Cleanup
End Sub
I cant tell what youre after is this. You need to be better at utilizing recordsets and how to use a string value as your sql statement.
You also didnt need to create a variable to store the textbox value in- you can use it directly in your sql statement.
Also it is very important to have good error handling as hanging recordset objects can be quite a pain in the ass.
EDIT - Ill expand on other ways to use string sql statements within VBA
DoCmd.RunSQl strSql
Or
DoCmd.Execute strSql
Both of these are great for UPDATE's or INSERT's.
Then, like Gustav pointed out, you have various D functions that are basically compact queries with some limitations. However, they often save you the trouble of having to do all the typing that is involved with opening,utlizing and closing records sets. Even though the D functions seem limited, I have often nested a few to get join results out of. Just a matter of imagination.
Look at this nifty site for function details -
https://www.techonthenet.com/access/functions/index.php
You don't need a query to do this. Just set the ControlSource of text2:
=DLookup("FirstName","Employee","EmployeeId=" & [text_in] & "")
I'm writing a function in Excel VBA to execute a stored queries on a database created using MS Access 2003. The code works when the stored query is a simple query, but NOT if the query is a UNION. For example, I'm using the following code to execute the stored queries:
Public Function QueryDB()
Dim cn As Object
Dim strConnection As String
Set cn = CreateObject("ADODB.Connection")
' Hard code database location and name
strConnection = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=\\server1\myDatabase.mdb"
' Open the db connection
cn.Open strConnection
' Create call to stored procedure on access DB
Dim cmd As Object
Set cmd = CreateObject("ADODB.Command")
cmd.CommandType = adCmdStoredProc
cmd.CommandText = "testQuery"
cmd.ActiveConnection = cn
' Execute stored query
Dim rs As ADODB.Recordset
Set rs = cmd.Execute()
MsgBox rs.Fields(0) ' prints as expected
QueryDB2 = rs.Fields(0)
' close connections
rs.Close
Set rs = Nothing
cn.Close
Set cn = Nothing
End Function
If testQuery is a simple query (e.g., does not use UNION), then data is returned as expected. However, if the testQuery contains a UNION, then the Excel VBA code fails (and no particular error is returned). How can I work-around this issue? I'd like to avoid writing the SQL statement in VBA.
Consider using ADO's Open Recordset method. Usually, Execute are for action commands (append/update/delete, stored procedures, etc.). Additionally, if Execute returns a recordset it is only a forward-only (i.e, snapshot with no cursor), read-only recordset without the facilities of MoveNext, RecordCount, Update.
Dim cn As Object
Dim rst As Object
Dim strConnection As String
Set cn = CreateObject("ADODB.Connection")
Set rst = CreateObject("ADODB.Recordset")
' Hard code database location and name
strConnection = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=\\server1\myDatabase.mdb"
' Open the db connection
cn.Open strConnection
' Open the recordset
rst.Open "testQuery", cn
Sheets(1).Range("A2").CopyFromRecordset rst
' Close recordset and db connection
rst.Close
cn.Close
Are you still struggling with this? Try using an ODBC Query. Follow the steps listed here.
http://translate.google.pl/translate?js=n&prev=_t&hl=pl&ie=UTF-8&layout=2&eotf=1&sl=pl&tl=en&u=http%3A%2F%2Fafin.net%2FKsiazkaSQLwExcelu%2FGraficznyEdytorZapytanSqlNaPrzykladzieMsQuery.htm
Make sure you have no nulls in your Union and if you do, you must use the NZ Function to convert nulls into zeros.
If I have a query that I have created using VBA:
dim SQL as string
dim rs as recordset
dim db as database
SQL = "SELECT ... FROM ..."
Set db = CurrentDb
Set rs = db.OpenRecordset(SQL, dbOpenDynaset)
At the end of my sub I would always do the following:
rs.close
set rs = nothing
My question is, do I need to SQL ="" or something of that like? I think my confusion originally came from the fact that I haven't used set SQL in my code.
and if I do clear these strings, then, is there a 'best' way?
Since you're not opening a connection to either CurrentDb or the SQL string, there's no need to close them. However, you are opening a recordset, so that should be closed. It wouldn't harm anything to set SQL = "", but it's not going to actually do anything constructive.
As far as a "best way", I think you've already got it. At the end of your sub, or before any code that might prematurely exit it, just put:
rs.close
set rs = nothing
I'm using an Access front-end for an Microsoft SQL back-end.
The problem I'm facing, is that I'm inserting data with an adodb connection. I use this on multiple forms. On the first form it works, on the second form it works, on the third form it also works. But on the fourth form I get an: 'ODBC: Call failed' error.
You might think I made some kind of typing error, but that is not the issue. When I start with form four I can insert the data.
So long story short, after 3 inserts on different form, I get that odbc error. I don't know what the problem is.
Dim Query As String
Dim rs As ADODB.Recordset
Dim cn As ADODB.Connection
Set cn = New ADODB.Connection
Set rs = New ADODB.Recordset
Query = "SELECT MAX(ID) From dbo_Controle"
rs.Open Query, CurrentProject.Connection
rs.MoveFirst
ID = rs.Fields(0).Value
Query = "INSERT INTO dbo_Controle VALUES (" & ID + 1 & ",'" & Me.txtControleTime & "')"
Set cn = CurrentProject.Connection
Debug.Print (Query)
cn.Execute Query
rs.Close
cn.Close
Set rs = Nothing
Set db = Nothing
This is the code I am using on different forms with different queries.
I was having the same issue, and was able to fix it by using CurrentProject.AccessConnection