I have made a sort field formula in the record sort expert as follows:

 

if {?Sort by} = 'Employer' then {dhc_sl_transactions.ST_COPYCUST} else
if {?Sort by} = 'Date' then ToText({dhc_sl_transactions.ST_DATE},"yyyy-MM-dd") else
if {?Sort by} = 'Description' then {dhc_sl_transactions.ST_DESCRIPTION}else
if {?Sort by} = 'Invoice Number' then {dhc_sl_transactions.ST_HEADER_REF}else
if {?Sort by} = 'Amount' then ToText({dhc_sl_transactions.ST_UNALLOCATED},0000000000.00)

 

I now want to add an extra parameter called ?Sort Direction which can either be 'Ascending' or 'Descending' and will perform the above sort in the direction specified.

 

What is the best way to do this.

 

Thanks