Storing byte array in MySQL Blob with VBA

问题:

Anybody have some VBA code that will store a byte array into a MySQL blob column?

回答1:

Here is some code. Requires a reference to Microsoft Active Data Objects 2.x Library. It uses the OLE DB provider for MySQL (Might need to install that on the client machine).

Sub StoreBLOB(data() As Byte, key As Double)
'stores the BLOB byte array into the row identified by the key
'requires reference to Microsoft Active Data Objects 2.x Library

On Error GoTo handler:

    Dim con As New ADODB.Connection
    Dim rs As New ADODB.Recordset
    Dim conStr As String
    Dim strSQL As String

    'have it return only the record you want to store your blob
    strSQL = strSQL & "SELECT * FROM YOURTABLE WHERE KEY = " & key

    'setup connection
    conStr = conStr & "Provider=MySQLProv;"
    conStr = conStr & "Data Source=mydb;"
    conStr = conStr & "User Id=myUsername;"
    conStr = conStr & "Password=myPassword;"

    con.ConnectionString = conStr
    con.Open

    rs.Open strSQL, con, adOpenDynamic, adLockOptimistic

    If rs.RecordCount > 1 Then
        Err.Raise 1001, "StoreBLOB", "Too many records returned from dataset.  Check to make sure you have the right key value"
    Else
        Err.Raise 1002, "StoreBLOB", "No Records found that match the key"
    End If

    rs.Fields("BLOBFIELDNAME").Value = data
    rs.Update 'store the contents to the database

    rs.Close
    con.Close
    Set rs = Nothing
    Set con = Nothing

Exit Sub
handler:
    Err.Raise 1003, "StoreBLOB", "Unexpected Error in StoreBLOB.  Check that server is running"
End Sub

回答2:

Assuming you are using ADO to access mysql, there's a KB article on the subject.

回答3:

I have some code, I replicated the mysql_real_escape_string_quote C function in VBA so that one can escape the necessary characters and build your SQL as you would for regular text:

Function mysql_real_escape_string_quote(toStr() As Byte, fromStr() As Byte, length As Long, quote As String) As Long
    mysql_real_escape_string_quote = 0
    Dim CharMap() As Byte: CharMap = StrConv(String(256, 0), vbFromUnicode)
    CharMap(0) = Asc("0"): CharMap(39) = Asc("'"): CharMap(34) = Asc(""""): CharMap(8) = Asc("b"): CharMap(10) = Asc("n"): CharMap(13) = Asc("r"):
    CharMap(9) = Asc("t"): CharMap(26) = Asc("z"): CharMap(92) = Asc("\"): CharMap(37) = Asc("%"): CharMap(95) = Asc("_"):

    Dim i As Long: Dim n As Long: n = 0
    If length > UBound(fromStr) + 1 Then Exit Function
    For i = 0 To length - 1  '---count escapable chars before redim---
        n = n + 1
        If CharMap(fromStr(i)) <> 0 Then n = n + 1
    Next i

    ReDim toStr(n - 1) As Byte
    n = 0
    For i = 0 To length - 1  '---test chars---
        If CharMap(fromStr(i)) = 0 Then
            toStr(n) = fromStr(i)
        Else                        '---escape char---
            toStr(n) = Asc(quote): n = n + 1
            toStr(n) = CharMap(fromStr(i))
        End If
        n = n + 1
    Next i
    mysql_real_escape_string_quote = n
End Function

Function mysql_real_escape_string(InputString As String) As String
    mysql_real_escape_string = ""
    Dim toStr() As Byte: Dim fromStr() As Byte
    fromStr = StrToChar(InputString)
    If mysql_real_escape_string_quote(toStr, fromStr, UBound(fromStr) + 1, "\") = 0 Then Exit Function
    mysql_real_escape_string = StrConv(toStr(), vbUnicode)
End Function

Function StrToChar(str As String) As Byte()
    Dim ans() As Byte
    ans = StrConv(str, vbFromUnicode)
    ReDim Preserve ans(Len(str)) As Byte
    ans(Len(str)) = 0
    StrToChar = ans
End Function

Sub testit()
    Dim toStr() As Byte: Dim fromStr() As Byte
    fromStr = StrToChar("hello world's")
    MsgBox (mysql_real_escape_string_quote(toStr, fromStr, UBound(fromStr) + 1, "\"))
    MsgBox (mysql_real_escape_string("hello world's"))
    For i = 0 To UBound(toStr)
        Debug.Print i & " " & toStr(i)
    Next i
End Sub

It's been optimized for large amounts of data without a ridiculous amount of conditionals (ifs).