Q:

Binary(16) as primary key: Lightswitch recognizes GUID but can't write them correctly

We must use GUIDs, identifying records for an export from SQL Server to MySQL. We've got a table in MySQL like this:
CREATE TABLE IF NOT EXISTS `images` (
  `idImage` binary(16) NOT NULL,
  `caption` varchar(1000),
  `preview` blob,
  `lastModified` datetime NOT NULL,
  PRIMARY KEY (`idImage`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

And insert data by this:
INSERT INTO `images` 
VALUES (
  -- .NET: Guid.Parse("12345678-1234-1234-1234-123456789001")
  UNHEX(REPLACE('78563412-3412-3412-1234-123456789001','-','')),
  'My first sample image',
  NULL,
  '2014-08-26 15:51:25'
);

After I setup the datasource in Lightswitch I got this:

Lightswitch recognizes my GUID primary key!!! Simply Awesome :-)
Here's the screen:

Yeah! That's great! 
But now, I'd like to CRUD:

I cannot create a new record. Lightswitch says: Data too long for column 'idImage' at row 1
I cannot update or delete any exisiting record. Lightswitch says: Another user has deleted this record. 

What did go wrong here? 

A:

This problem is easy to solve. You have to tell the MySQL-Connector to use another (older) illustration of GUIDs.
Normally this is done by adding 
Old Guids=true;

to the connection string.
In your case (Lightswitch project) you have to change this option with the "Data Source Wizard". 
You'll find this in the menu:
Attach Data Source Wizard > Connection Properties >Advanced Properties

That's it!

