MySQL Bugs: #56253: myodbc5.dll crashed when the .Update method is used with more than 2 fields

Bug #56253	myodbc5.dll crashed when the .Update method is used with more than 2 fields
Submitted:	25 Aug 2010 13:30	Modified:	9 Aug 2022 11:00
Reporter:	Andrei Iancu	Email Updates:
Status:	Can't repeat	Impact on me:	None
Category:	Connector / ODBC	Severity:	S2 (Serious)
Version:	5.1.8	OS:	Windows (Windows XP SP3)
Assigned to:	Bogdan Degtyariov	CPU Architecture:	Any
Tags:	connector odbc crash vb6 visual basic .update method strings

Description:
For an unknown reason, myodbc5.dll crashes when i try to update some fields with the update method from ADO, using the ODBC Driver. This does not happen always, though. If i have fields that are integers or floats, the data is updated. If i have fields that are string, .update also works. BUT, if i have a mix of strings and integers, it crashes and crashed vb6 ide along with it. Source code is available and database structure too.

How to repeat:
Create a schema witha table (let's say Products) containing some some INTEGER columns, some FLOAT columns,  some TEXT columns. 

Let's name the database 'test_db'.

After that, let's connect from vb6 through an ODBC driver 

Driver={mySQL ODBC 5.1 Driver};Server=192.168.1.1;Port=3306;Option=3;Database=test_db;Uid=root;Pwd=some_root_password;

Now, let's create a new entry in the schema....

ComandaSQL = "SELECT * FROM Products;"
    
vDBRecordset.Open (ComandaSQL), vDBConnection, adOpenDynamic, adLockOptimistic
 With vDBRecordset
     .AddNew
       !idproduct = 10             ' integer
       !priceeuro = 40             ' float
       !vatproc = 24               ' float
       !code = "testcode123"       ' string
       !model = "testmodel123"     ' string
       !comments = "200 dpi mode"  ' string
    .Update
 End With
If vDBRecordset.state = 1 Then vDBRecordset.Close

Everything works until i hit the .Update line... then it crashes.

Suggested fix:
It seems to me there's a problem with the 'float' data type, somewhere. It is not handled correctly. VB6 does not have float, is has Double and Currency.
The connector should be able to convert other data types to float....

crash of screenshot

Attachment: untitled.jpg (image/pjpeg, text), 200.02 KiB.

finally, found the fix for this, after maaaaaany hours spent on the net, thought i might share it with you :

you have to set the following property before you use the OPEN method of the connection class.... 

     vDBConnection.CursorLocation = adUseClient

then, you can use open....

     vDBConnection.Open (vConnectionString), , , 0

and presto ! it works flawlessly !

That is very good that there is workaround, but the bug still exists probably. Did I understand correctly that your application didn't crash with previous driver version - 5.1.6, and appeared with the update to version 5.1.7?

unfortunately, the the app. used to crash in 5.1.6 too.... i downloaded the more recent 5.1.7 and the problem was still there...

With the versions 5.1.8/5.1.9 Access doesn't crash anymore, but it inserts 0 for idproduct instead of 10 as indicated in the test case.

CREATE TABLE `bug56253` (
`idproduct`  int NULL ,
`priceeuro`  float NULL ,
`vatproc`  float NULL ,
`code`  varchar(32) NULL ,
`model`  varchar(64) NULL ,
`comments`  text NULL ,
PRIMARY KEY (`idproduct`));

' VB Test case
Sub bug56253()
    Dim conn As ADODB.Connection
    Set conn = New ADODB.Connection
    
    Dim rs As ADODB.Recordset
    Set rs = New ADODB.Recordset
    
    conn.Open "DSN=test", "*******", "********", 0
    rs.Open "SELECT * FROM bug56253", conn, adOpenDynamic, adLockOptimistic
    With rs
         .AddNew
           !idproduct = 10             ' integer
           !priceeuro = 40             ' float
           !vatproc = 24               ' float
           !code = "testcode123"       ' string
           !model = "testmodel123"     ' string
           !comments = "200 dpi mode"  ' string
        .Update
    End With
End Sub

Bug #62365 is marked as a duplicate of this one.
The current report has much simpler test case.

Posted by developer:
 
This bug is no longer repeatable with the current line of Connector/ODBC 8.0.