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Thread: Lianja 6.3 now supports oledb drivers as well as ODBC

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    Lianja Development Team barrymavin's Avatar
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    Lianja 6.3 now supports oledb drivers as well as ODBC

    In Lianja 6.3 "oledb" can be used as an alternative to "ODBC" with Virtual Tables.

    You can now use the "vfpoledb" driver to access VFP data concurrently while VFP is.

    This is windows specific but enables you to run Lianja Apps alongside VFP applications sharing the data.

    In the CONNSTR of the Virtual Table you specify the CONNSTR (Connection String) of an oledb driver like this:

    Code:
    use orders connstr "oledb:Provider=VFPOLEDB;Mode=Share Deny None;Data Source=c:\users\barrymavin\northwind.dbc;Exclusive=No" as select * from orders where customerid='BLONP'
    list
    use customers connstr "oledb:Provider=VFPOLEDB;Mode=Share Deny None;Data Source=c:\users\barrymavin\northwind.dbc;Exclusive=No" 
    list
    This creates a VT connected to the VFP database northwind using the VFP oledb driver.

    Records can be updated concurrently with VFP through the UI or using the Lianja/VFP REPLACE statement.

    Data is buffered and Lianja handles optimistic locking in the same way as it does with ODBC.

    The advantage of using oledb rather than ODBC is that Lianja will fetch data as needed rather than fill the cursor when the VT is opened.

    VFP itself buffers records so if you want to see any data that was updated in Lianja you should SET LOCK ON in your VFP code which causes all records to be force read from disk. if your VFP code uses RLOCK() (which is not needed in Lianja as it handles automatic record locking) then that always rereads the active record so you will see changes to it made by Lianja.

    Note that Lianja does not yet handle the sharing of "G" datatypes with VFP (Images etc) but will soon.

    You can lookup oledb and ODBC connection strings at:
    https://www.connectionstrings.com

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    Currently Lianja converts data to uff-8 as that is the universal data format it uses across desktop and web apps.

    I will be adding VT properties to better handle customization of this.
    Last edited by barrymavin; 2021-09-23 at 05:17.
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