SQL Server Bulk insert of CSV file with inconsistent quotes

It isn't possible to do a bulk insert for this file, from MSDN:

To be usable as a data file for bulk import, a CSV file must comply with the following restrictions:

• Data fields never contain the field terminator.
• Either none or all of the values in a data field are enclosed in quotation marks ("").

(http://msdn.microsoft.com/en-us/library/ms188609.aspx)

Some simple text processing should be all that's required to get the file ready for import. Alternatively your users could be required to either format the file according to the se guidelines or use something other than a comma as a delimiter (e.g |)

You are going to need to preprocess the file, period.

If you really really need to do this, here is the code. I wrote this because I absolutely had no choice. It is utility code and I'm not proud of it, but it works. The approach is not to get SQL to understand quoted fields, but instead manipulate the file to use an entirely different delimiter.

EDIT: Here is the code in a github repo. It's been improved and now comes with unit tests! https://github.com/chrisclark/Redelim-it

This function takes an input file and will replace all field-delimiting commas (NOT commas inside quoted-text fields, just the actual delimiting ones) with a new delimiter. You can then tell sql server to use the new field delimiter instead of a comma. In the version of the function here, the placeholder is <TMP> (I feel confident this will not appear in the original csv - if it does, brace for explosions).

Therefore after running this function you import in sql by doing something like:

BULK INSERT MyTable
FROM 'C:\FileCreatedFromThisFunction.csv'
WITH
(
FIELDTERMINATOR = '<*TMP*>',
ROWTERMINATOR = '\n'
)

And without further ado, the terrible, awful function that I apologize in advance for inflicting on you (edit - I've posted a working program that does this instead of just the function on my blog here):

Private Function CsvToOtherDelimiter(ByVal InputFile As String, ByVal OutputFile As String) As Integer

        Dim PH1 As String = "<*TMP*>"

        Dim objReader As StreamReader = Nothing
        Dim count As Integer = 0 'This will also serve as a primary key'
        Dim sb As New System.Text.StringBuilder

        Try
            objReader = New StreamReader(File.OpenRead(InputFile), System.Text.Encoding.Default)
        Catch ex As Exception
            UpdateStatus(ex.Message)
        End Try

        If objReader Is Nothing Then
            UpdateStatus("Invalid file: " & InputFile)
            count = -1
            Exit Function
        End If

        'grab the first line
    Dim line = reader.ReadLine()
    'and advance to the next line b/c the first line is column headings
    If hasHeaders Then
        line = Trim(reader.ReadLine)
    End If

    While Not String.IsNullOrEmpty(line) 'loop through each line

        count += 1

        'Replace commas with our custom-made delimiter
        line = line.Replace(",", ph1)

        'Find a quoted part of the line, which could legitimately contain commas.
        'In that case we will need to identify the quoted section and swap commas back in for our custom placeholder.
        Dim starti = line.IndexOf(ph1 & """", 0)
        If line.IndexOf("""",0) = 0 then starti=0

        While starti > -1 'loop through quoted fields

            Dim FieldTerminatorFound As Boolean = False

            'Find end quote token (originally  a ",)
            Dim endi As Integer = line.IndexOf("""" & ph1, starti)

            If endi < 0 Then
                FieldTerminatorFound = True
                If endi < 0 Then endi = line.Length - 1
            End If

            While Not FieldTerminatorFound

                'Find any more quotes that are part of that sequence, if any
                Dim backChar As String = """" 'thats one quote
                Dim quoteCount = 0
                While backChar = """"
                    quoteCount += 1
                    backChar = line.Chars(endi - quoteCount)
                End While

                If quoteCount Mod 2 = 1 Then 'odd number of quotes. real field terminator
                    FieldTerminatorFound = True
                Else 'keep looking
                    endi = line.IndexOf("""" & ph1, endi + 1)
                End If
            End While

            'Grab the quoted field from the line, now that we have the start and ending indices
            Dim source = line.Substring(starti + ph1.Length, endi - starti - ph1.Length + 1)

            'And swap the commas back in
            line = line.Replace(source, source.Replace(ph1, ","))

            'Find the next quoted field
            '                If endi >= line.Length - 1 Then endi = line.Length 'During the swap, the length of line shrinks so an endi value at the end of the line will fail
            starti = line.IndexOf(ph1 & """", starti + ph1.Length)

        End While

            line = objReader.ReadLine

        End While

        objReader.Close()

        SaveTextToFile(sb.ToString, OutputFile)

        Return count

    End Function