Removing "~TDS_ODBC_ON" from connection option_flag2

[alexloney]

This is a change I have been using in my version of FreeTDS for a while. Recently, I've been updating our FreeTDS version to the latest FreeTDS version and am pushing this change back to the base FreeTDS.

When the following flag is set:

connection->option_flag2 &= ~TDS_ODBC_ON;

If we have a Table-valued function with the following:

CREATE FUNCTION [dbo].[fnSomeFunction] () RETURNS @someReturnTbl TABLE (
  col_name varchar(max)
)
AS
BEGIN 
    declare @some_data_base64 varchar(max) = 'dGVzdAo=' 
    declare @some_data_bin varbinary(max) 

    set @some_data_bin = cast('' as xml).value(
            'xs:base64Binary(sql:variable("@some_data_base64"))', 
            'varbinary(max)'
        )
    RETURN
END


CREATE PROCEDURE SomeProcedure
AS
BEGIN
    declare @tmpTable table (
        col_name varchar(max)
    )
    declare @tmpName varchar(max)

    declare someCsr cursor for select col_name from fnSomeFunction()
    
    open someCsr
    fetch next from someCsr into @tmpName
    
    while @@FETCH_STATUS = 0
    begin
        insert into @tmpTable (col_name)
        values (@tmpName)
    
        fetch next from someCsr into @tmpName
    end

    close someCsr 
    deallocate someCsr 
END
GO

If I then try to execute SomeProcedure through FreeTDS, I receive the following error message:

Error in procedure 'SomeProcedure'
SELECT failed because the following SET options have incorrect settings: 'CONCAT_NULL_YIELDS_NULL, ANSI_WARNINGS, ANSI_PADDING'. Verify that SET options are correct for use with indexed views and/or indexes on computed columns and/or filtered indexes and/or query notifications and/or XML data type methods and/or spatial index operators.

The error message is specifcally related to this line in the function:

set @some_data_bin = cast('' as xml).value(
        'xs:base64Binary(sql:variable("@some_data_base64"))', 
        'varbinary(max)'
    )

After removing the ~TDS_ODBC_ON flag being set, I'm able to execute the SomeProcedure stored procedure without issue.

[freddy77]

Hi. Yes, known issue but for compatibility this change cannot be accepted in this format. That is there should be an option to enable ODBC compatibility (obviously disabled by default).
I suppose a freetds.conf option won't hurt, a DBSETODBCCOMPAT (or similar) for LOGINREC won't hurt either. I won't like an environment variable. I won't personally like a configure options (or any similar compile thing causing multiple ABIs).
The current suggested solution is to use manual USE statements after the connection to override settings to ODBC ones.
I don't know your use case so how would you prefer the setting I have no idea.

[alexloney]

Thank you for the feedback, I'll update the the pull request to change it to a freetds.conf option soon.