ROUND

Round a number (up or down) to the nearest integer. Optionally, specify a decimal precision for the rounding.

ROUND(number [, places])

If only number is specified, the function rounds to the nearest whole number. If places is also specified, the function rounds to the nearest number with that many decimal places of precision.

The first argument can be any numeric data type. However, if both arguments are used, the first argument cannot be a floating-point data type. If you want to round a floating-point number to a specific decimal precision, you must explicitly cast the number to a decimal data type. For example:

premdb=# create table floats (f1 float8);
CREATE TABLE
premdb=# insert into floats values(1234567890.12334567890);
INSERT 0 1
premdb=# select round(f1,3) from floats;
ERROR:  function round(double precision, integer) does not exist
LINE 2: select round(f1,3) from floats;
               ^
HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
premdb=# select round(f1::decimal(19,5),3) from floats;
     round      
----------------
 1234567890.123
(1 row)

Examples

Round up to the nearest whole number:
premdb=# select round(2.5) from sys.const;
 round 
-------
     3
(1 row)
Round up with a precision of two decimal places:
premdb=# select round(2.5,2) from sys.const;
 round 
-------
  2.50
(1 row)
The following example rounds the results of an AVG function to a precision of three decimal places.
premdb=# SELECT seasonid, AVG(SUBSTR(ftscore,3,1)::INT), 
ROUND(AVG(SUBSTR(ftscore,3,1)::INT),3) roundgoals FROM match GROUP BY seasonid ORDER BY 2;
 seasonid |            avg            | roundgoals 
----------+---------------------------+------------
       15 | 0.99736842105263157894736 |      0.997
       14 | 1.02368421052631578947368 |      1.024
       13 | 1.06578947368421052631578 |      1.066
        9 | 1.06578947368421052631578 |      1.066
        7 | 1.06842105263157894736842 |      1.068
       18 | 1.07368421052631578947368 |      1.074
        4 | 1.07368421052631578947368 |      1.074
        3 | 1.07792207792207792207792 |      1.078
       17 | 1.07894736842105263157894 |      1.079
        1 | 1.08008658008658008658008 |      1.080
        5 | 1.08157894736842105263157 |      1.082
...
The following example rounds DECIMAL values to the nearest integer.
premdb=# SELECT atid, htid, atid/htid::DEC(7,2), 
ROUND(atid/htid::DEC(7,2)) FROM team;
 atid | htid |  ?column?   | round 
------+------+-------------+-------
   51 |    2 | 25.50000000 |    26
   52 |    3 | 17.33333333 |    17
   53 |    4 | 13.25000000 |    13
   54 |    5 | 10.80000000 |    11
   55 |    6 |  9.16666666 |     9
   56 |    7 |  8.00000000 |     8
   57 |    8 |  7.12500000 |     7
   58 |    9 |  6.44444444 |     6
   59 |   10 |  5.90000000 |     6
   60 |   11 |  5.45454545 |     5
   61 |   12 |  5.08333333 |     5
   62 |   13 |  4.76923076 |     5
   63 |   14 |  4.50000000 |     5
...