Microsoft Access does consider Varchar types with a size greater than 255 as Memo objects. However, Memo objects cannot be used as JOIN conditions. In such scenarios the query will fail with the following error: “Cannot JOIN on Memo, OLE or Hyperlink Object”.
Depending on the provider you are using and your use case, there are a few options that would solve the issue:
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Setting the DefaultColumnSize=255 in the Other connection property. This property will limit all column sizes to a maximum of 255 characters.
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Modifying the datatype size via custom schemas.
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Using Access passthrough mode.
Additional details regarding enabling pass-through mode in Access can be found on the following link: