BearFF

In my last post on using ActiveX Data Objects (ADO) with Excel VBA, I demonstrated some code to load a Recordset, filter the Recordset using the Recordset’s Filter Prpoerty, and copy the Filtered Recordset to a Worksheet using the CopyFromRecordset Method of the Range Object.

I put a link to the blog post on the Excel VBA and Users Group on LinkedIn. To our good fortune, James Wilson was reading. James responded with some nice comments and some very good code of his own. I was impressed and asked James if he would like to do a write up to post on the blog.

James kindly accepted my offer as follows in James’ words. Take it away James!



Bringing the full power of SQL to bear in Excel

James Wilson
September 13, 2014

“I feel the need, the need for speed.” Top Gun

I love Excel, but sometimes you just want a bit more power to analyse your data. My favourite tool for analysing large quantities of data has always been SQL. While Microsoft includes MS Query in Excel out-of-the-box, it does have many limitations and is relatively slow. Using VBA and ADO is the next logical step.

The code below is the latest incarnation of a general purpose SQL function I’ve been using for the last five years or so. For me the data is the thing – I want to be able to start querying my data using SQL without having to start coding from scratch each time. Just copy and paste into a module in your workbook, and you’re ready to go.

Code first then some explanation:

Function SQL(ByVal SQLstr As String, ByVal Destination As String, Optional ByVal ConnectionString As String) As Boolean

    On Error GoTo ErrorHandler
    Application.ScreenUpdating = False
    Application.Calculation = xlCalculationManual
    Application.DisplayAlerts = False

    Dim myConnection As Object
    Dim myRecordSet As Object
    Dim myQueryTable As QueryTable

    ThisWorkbook.Sheets(Destination).Activate
    ThisWorkbook.Sheets(Destination).Cells.Delete

    If ConnectionString = "" Then ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" & ThisWorkbook.FullName & ";Extended Properties=Excel 12.0"
    
    Set myConnection = CreateObject("ADODB.Connection")
    Set myRecordSet = CreateObject("ADODB.Recordset")
    
    myConnection.ConnectionString = ConnectionString
    myConnection.Open
    myRecordSet.ActiveConnection = ConnectionString
    myRecordSet.Source = SQLstr
    myRecordSet.Open
    
    Set myQueryTable = Sheets(Destination).QueryTables.Add(Connection:=myRecordSet, Destination:=Range("'" & Destination & "'!a1"))
    myQueryTable.Refresh
    
    If myRecordSet.State <> adStateClosed Then myRecordSet.Close
    If Not myRecordSet Is Nothing Then Set myRecordSet = Nothing
    If Not myConnection Is Nothing Then Set myConnection = Nothing
    
    Err.Clear
ErrorHandler:
    If Err Then
        Sheets(Destination).Cells(1, 1) = "SQL Error: " & Err.Description
        SQL = False
    Else
        SQL = True
    End If
    
    Application.ScreenUpdating = True
    Application.Calculation = xlCalculationAutomatic
    Application.DisplayAlerts = True
End Function

I wrote this as a VBA function rather than a sub procedure, because I wanted to be able to trap errors in the calling procedure. It is a really a matter of preference whether you like your functions to return True or False (lines 28 and 30). I’ve chosen to return True if it worked, so I’d call it using coding something like:

Sub test()
    DidItWork = SQL("SELECT * FROM [Sheet1$] WHERE [Sheet1$].[date] > #01/03/2014#", "Sheet2")
    If DidItWork = False Then … 'Do some error handling
End Sub

Basically this function sets up an ADO link to a data source, executes an SQL query on that data, and returns the results of that query to a worksheet of our choice in the current workbook using a query table.

When you call this function (line 1), you pass a string with your SQL query, a string with the name of the worksheet you want the data to be returned to, and optionally a connection string to the data source. By default the data source is the workbook the code is in. That’s right – you can use SQL to query data in other tabs in the same workbook (make sure your workbook is saved first).

If you find that most of the time you are querying a corporate database or other data source, then you’d just tweak line 15 of the coding to default to the connection string to the data source you are using most often.

Lines 4 to 6 and 42 to 44 are just the standard VBA codes that you’d put in to speed up any bit of coding. If you are calling this function and have these bits of coding in the calling procedure, then you can safely delete these lines from this function.

Lines 8 to 10 are to set up a local connection and recordset object (we’re going to use ADO to get our data), and a query table (which we are going to use to return the results of the SQL query to Excel).

The way this function is written, your data output is always going to be a worksheet in the current workbook in Cell A1. You can have no other data in this worksheet as Lines 12 to 13 delete the contents of the worksheet, before it is refreshed again with the query table set up in Line 26.

Line 17 to 27 is the meat of the function, setting up an ADO link and returning the data using a query table.

Lines 29 to 31 are to tidy up objects and connections. Line 36 is to give you a clue if you’ve made an error in your SQL.

So I’ve a personal library function that allows me to use SQL in Excel without much further thought – what do I do with it? Let me give a few simple examples to give an idea of the possibilities.

  1. Treat my current spreadsheet a bit like a mini-database and run queries on it – that would be much harder to do just using VBA or manually copying and pasting.
  2. Suck data out of multiple corporate databases and spreadsheets and join it together. You don’t need even to open the spreadsheets to get the data (as I said to start with – it’s all about speed and power). So for example let’s say you have one spreadsheet from your sales guys with sales volumes, and you have another spreadsheet with the confidential prices for each customer, then you can do a bit of SQL coding like:
    DidItWork = SQL(“SELECT A.*, B.[Price], A.[Volume]*B.[Price] as [Revenue] from [C:\Sales Volumes.xlsx].[Data$] A LEFT OUTER JOIN [F:\Prices.xlsx].[Sheet1$] B ON A.[Product] = B.[Product] AND A.[Customer No] = B.[Customer] “, “Sales Forecast”)
    So I’m using SQL aliases A and B for brevity, and by using multipart identifiers specifying the full path and filename of the Excel workbooks I can suck data out of any file I have access to. Note if you specify the data source fully, the connection string ADO uses is virtually irrelevant.
  3. By using For…Next loops in VBA and a bit of text manipulation and the SQL command UNION I can consolidate multiple similar data sources simply. So using a string variable like below in a loop:

mySQLstring = mySQLstring & ” UNION ” & …
Good for consolidating budgets submitted in a similar format.

The limitation is really your knowledge of SQL. Beware of missing spaces and extra commas in your SQL if you are using the VBA & _ to join long strings together to form your SQL.


Tidy Up

Thanks James – great job! How do you use ADO, SQL, Recordsets and QueryTables in your Projects?

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