SQL : select one column if two columns are equal, else select both -

i have following sql select problem:

i have 2 columns positive threshold , negative threshold (among several other columns name, ids.... ).

• if (absolute) value same (multiply -1) want select positive threshold column [threshold].

• if values different, want select 2 columns [positivethreshold] , [negativethreshold].

thank in advance.

select null [threshold], positivethreshold, negativethreshold  table  negativethreshold null  or (positivethreshold + negativethreshold) <> 0  union select positivethreshold, null, null table  (positivethreshold + negativethreshold) = 0