Can't you skip the UNIONing and do this with something like
where (Z_A_nr is NULL
AND Z_umfang = '900' AND Z_blaenge = '2340' AND
Z_durch_soll IN ('286.1', '286.15', '286.20', ...)
AND Z_status = 'zcu'
AND (((Z_durch_soll+0.25)-Z_durch_ist) / 2) >= 0.085
AND (((Z_durch_soll+0.25)-Z_durch_ist) / 2) > 0.12)
?
I'm not sure whether the difference in the last output expression
(Z_durch_soll+0.25 in the first UNION'd select, Z_durch_soll+0.2
in the rest) is intentional or a typo. If it's intentional, you
could write it as something like
CASE WHEN Z_durch_soll = '286.45' THEN Z_durch_soll+0.25
ELSE Z_durch_soll+0.2 END
regards, tom lane
