Oracle ROUND HALF EVEN [closed] - oracle

Question

Closed. This question needs to be more focused. It is not currently accepting answers.
Want to improve this question? Update the question so it focuses on one problem only by editing this post.
Closed 5 years ago.
Improve this question
Is there any Oracle function to perform the ROUND HALF EVEN?
I've found this post MySQL round half however I couldn't make it work in Oracle
CREATE FUNCTION roundHalfEven (numberToRound IN NUMBER, roundPrecision IN NUMBER)
RETURN NUMBER
IS roundedNumber NUMBER;
BEGIN
DECLARE digitEvenOdd NUMBER;
DECLARE digitPosition NUMBER;
DECLARE digitToRound NUMBER;
DECLARE roundedNumber DECIMAL(20,6) DEFAULT 0;
SET digitPosition = INSTR(numberToRound, '.');
IF (roundingPrecision < 1) THEN
SET digitPosition = digitPosition + roundingPrecision;
ELSE
SET digitPosition = digitPosition + roundingPrecision + 1;
END IF;
IF (digitPosition > 0 AND digitPosition <= CHAR_LENGTH(numberToRound)) THEN
SET digitToRound = CAST(SUBSTR(numberToRound, digitPosition, 1) AS UNSIGNED);
SET digitPosition = digitPosition - 1;
IF (digitPosition > 0 AND digitPosition <= CHAR_LENGTH(numberToRound)) THEN
SET digitEvenOdd = CAST(SUBSTR(numberToRound, digitPosition, 1) AS UNSIGNED);
END IF;
END IF;
IF (digitToRound > -1) THEN
IF (digitToRound >= 5 AND digitEvenOdd IN (1,3,5,7,9)) THEN
SET roundedNumber = ROUND(numberToRound, roundingPrecision);
ELSE
SET roundedNumber = TRUNCATE(numberToRound, roundingPrecision);
END IF;
ELSE IF (roundingPrecision > 0) THEN
SET roundedNumber = numberToRound;
END IF;
RETURN(roundedNumber);
END;
/

Answer 1

SQL Fiddle
Oracle 11g R2 Schema Setup:
CREATE TABLE test_data( value ) AS
SELECT (LEVEL -11)/2 FROM DUAL CONNECT BY LEVEL <= 21;
Query 1:
SELECT value,
ROUND( value ),
CASE
WHEN MOD( ABS( value ), 2 ) = 0.5
THEN TRUNC( value )
ELSE ROUND( value )
END AS round_half_even
FROM test_data
Results:
| VALUE | ROUND(VALUE) | ROUND_HALF_EVEN |
|-------|--------------|-----------------|
| -5 | -5 | -5 |
| -4.5 | -5 | -4 |
| -4 | -4 | -4 |
| -3.5 | -4 | -4 |
| -3 | -3 | -3 |
| -2.5 | -3 | -2 |
| -2 | -2 | -2 |
| -1.5 | -2 | -2 |
| -1 | -1 | -1 |
| -0.5 | -1 | 0 |
| 0 | 0 | 0 |
| 0.5 | 1 | 0 |
| 1 | 1 | 1 |
| 1.5 | 2 | 2 |
| 2 | 2 | 2 |
| 2.5 | 3 | 2 |
| 3 | 3 | 3 |
| 3.5 | 4 | 4 |
| 4 | 4 | 4 |
| 4.5 | 5 | 4 |
| 5 | 5 | 5 |
Or as a function:
SQL Fiddle
Oracle 11g R2 Schema Setup:
CREATE TABLE test_data( value ) AS
SELECT (LEVEL -11)/20 FROM DUAL CONNECT BY LEVEL <= 21
/
CREATE FUNCTION round_half_even(
value NUMBER,
prec INTEGER DEFAULT 0
) RETURN NUMBER
IS
whole NUMBER := POWER( 10, -prec );
BEGIN
RETURN CASE
WHEN ABS( MOD( value, 2*whole ) ) = 0.5*whole
THEN TRUNC( value, prec )
ELSE ROUND( value, prec )
END;
END;
/
Query 1:
SELECT value,
ROUND( value , 1),
round_half_even( value, 1 )
FROM test_data
Results:
| VALUE | ROUND(VALUE,1) | ROUND_HALF_EVEN(VALUE,1) |
|-------|----------------|--------------------------|
| -0.5 | -0.5 | -0.5 |
| -0.45 | -0.5 | -0.4 |
| -0.4 | -0.4 | -0.4 |
| -0.35 | -0.4 | -0.4 |
| -0.3 | -0.3 | -0.3 |
| -0.25 | -0.3 | -0.2 |
| -0.2 | -0.2 | -0.2 |
| -0.15 | -0.2 | -0.2 |
| -0.1 | -0.1 | -0.1 |
| -0.05 | -0.1 | 0 |
| 0 | 0 | 0 |
| 0.05 | 0.1 | 0 |
| 0.1 | 0.1 | 0.1 |
| 0.15 | 0.2 | 0.2 |
| 0.2 | 0.2 | 0.2 |
| 0.25 | 0.3 | 0.2 |
| 0.3 | 0.3 | 0.3 |
| 0.35 | 0.4 | 0.4 |
| 0.4 | 0.4 | 0.4 |
| 0.45 | 0.5 | 0.4 |
| 0.5 | 0.5 | 0.5 |