EmptyColumnsToNull.fmfn

/*
 * =====================================================
 * @function EmptyColumnsToNull ( sqlResults; columnDelimiter; rowDelimiter; nullCharacter )
 *
 * @parameter sqlResults (string)
 * @parameter columnDelimiter (string)
 * @parameter rowDelimiter (string)
 * @parameter nullCharacter (string)
 *
 * @return string Return the SQL results with empty values changed to null
 *
 * @category list
 * @copyright 2015, Jason P. Scharf
 *
 * @version 1.0
 *
 * @dependencies NONE
 *
 * @purpose Prepare sql results for list manipulation functions.
 *
 * @notes
 * @/notes
 *
 * @changes
 * 2015-12-16, JPS, Created. [1.0.0]
 * @/changes
 * =====================================================
 */

Let (
    [
        /************************/
        /* Start Configuration **/
        /************************/

        /* CONSTANTS ************/
        Debug = False;

        // Default to ASCII code 31 ( 31, 037, 1F - US, Unit Separator )
        COL = If ( IsEmpty ( columnDelimiter ); Char ( 31 ); columnDelimiter );

        // Default to ASCII code 30 ( 30, 036, 1E - RS, Record Separator )
        ROW = If ( IsEmpty ( rowDelimiter ); Char ( 30 ); rowDelimiter );

        // Default to ASCII code 21 ( 21, 025, 15 - NAK, Negative Acknowledgement )
        NUL = If ( IsEmpty ( nullCharacter ); Char ( 21 ); nullCharacter )

        /************************/
        /* End Configuration ****/
        /************************/
    ];

        If (
            IsEmpty ( sqlResults );
                "";

            /* ELSE */

            Substitute (
                sqlResults & ROW;
                [
                    COL & COL;
                    COL & NUL & COL
                ];
                [
                    COL & COL;
                    COL & NUL & COL
                ];
                [
                    COL & ROW;
                    COL & NUL & ROW
                ];
                [
                    ROW & COL;
                    ROW & NUL & COL
                ]
            )
        )
)