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Oracle SQL: ROUND, ROUND_TIES_TO_EVEN, TRUNC, FLOOR, CEIL

floor(n) returns the largest integer equal to or less than n, i.e. floor(n) <= n
ceil(n) returns the smallest integer that is greater than or equal to n, i.e. ceil(n) >= n
set numformat 999990.000

with numbers as (
   select  12345.6789 num from dual union all
   select - 7777.77   num from dual union all
   select      0.5    num from dual union all
   select      0.05   num from dual union all
   select     -0.05   num from dual union all
   select     -0.005  num from dual union all
   select      3.05   num from dual union all
   select      3.005  num from dual union all
   select     -3.005  num from dual union all
   select     -3.04   num from dual union all
   select     -3.05   num from dual union all
   select     -3.06   num from dual union all
   select      4.04   num from dual union all
   select      4.05   num from dual union all
   select      4.06   num from dual union all
   select      4.005  num from dual union all
   select     -4.05   num from dual union all
   select     -4.005  num from dual
)
select
         num    ,

   trunc(num   ) "tr"   , round(num   ) "rd"   , round_ties_to_even(num   ) "ty"   ,
   trunc(num, 2) "tr 2" , round(num, 2) "rd 2" , round_ties_to_even(num, 2) "ty 2" ,
   trunc(num,-2) "tr -2", round(num,-2) "rd -2", round_ties_to_even(num,-2) "ty -2",

   ceil (num   ) "cl",
   floor(num   ) "fl"
from
   numbers;
--
--        NUM         tr         rd         ty       tr 2       rd 2       ty 2      tr -2      rd -2      ty -2         cl         fl
-- ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- ----------
--  12345.679  12345.000  12346.000  12346.000  12345.670  12345.680  12345.680  12300.000  12300.000  12300.000  12346.000  12345.000
--  -7777.770  -7777.000  -7778.000  -7778.000  -7777.770  -7777.770  -7777.770  -7700.000  -7800.000  -7800.000  -7777.000  -7778.000
--      0.500      0.000      1.000      0.000      0.500      0.500      0.500      0.000      0.000      0.000      1.000      0.000
--      0.050      0.000      0.000      0.000      0.050      0.050      0.050      0.000      0.000      0.000      1.000      0.000
--     -0.050      0.000      0.000      0.000     -0.050     -0.050     -0.050      0.000      0.000      0.000      0.000     -1.000
--     -0.005      0.000      0.000      0.000      0.000     -0.010      0.000      0.000      0.000      0.000      0.000     -1.000
--      3.050      3.000      3.000      3.000      3.050      3.050      3.050      0.000      0.000      0.000      4.000      3.000
--      3.005      3.000      3.000      3.000      3.000      3.010      3.000      0.000      0.000      0.000      4.000      3.000
--     -3.005     -3.000     -3.000     -3.000     -3.000     -3.010     -3.000      0.000      0.000      0.000     -3.000     -4.000
--     -3.040     -3.000     -3.000     -3.000     -3.040     -3.040     -3.040      0.000      0.000      0.000     -3.000     -4.000
--     -3.050     -3.000     -3.000     -3.000     -3.050     -3.050     -3.050      0.000      0.000      0.000     -3.000     -4.000
--     -3.060     -3.000     -3.000     -3.000     -3.060     -3.060     -3.060      0.000      0.000      0.000     -3.000     -4.000
--      4.040      4.000      4.000      4.000      4.040      4.040      4.040      0.000      0.000      0.000      5.000      4.000
--      4.050      4.000      4.000      4.000      4.050      4.050      4.050      0.000      0.000      0.000      5.000      4.000
--      4.060      4.000      4.000      4.000      4.060      4.060      4.060      0.000      0.000      0.000      5.000      4.000
--      4.005      4.000      4.000      4.000      4.000      4.010      4.000      0.000      0.000      0.000      5.000      4.000
--     -4.050     -4.000     -4.000     -4.000     -4.050     -4.050     -4.050      0.000      0.000      0.000     -4.000     -5.000
--     -4.005     -4.000     -4.000     -4.000     -4.000     -4.010     -4.000      0.000      0.000      0.000     -4.000     -5.000

See also

Using the Largest Reminder Method to round percentages so that their sum is 100 percent
Oracle SQL functions

Index