银行家对 BigQuery 的四舍五入

Question

简单的问题在BigQuery中如何使用银行四舍五入。

我唯一能找到的是：

方法不对但仍然有效：

CREATE TEMP FUNCTION test(num FLOAT64, decimalPlaces INT64)
RETURNS FLOAT64
LANGUAGE js AS """
    var d = decimalPlaces || 0;
    var m = Math.pow(10, d);
    var n = +(d ? num * m : num).toFixed(8); // Avoid rounding errors
    var i = Math.floor(n), f = n - i;
    var e = 1e-8; // Allow for rounding errors in f
    var r = (f > 0.5 - e && f < 0.5 + e) ?
    ((i % 2 == 0) ? i : i + 1) : Math.round(n);
    return d ? r / m : r;
""";


SELECT ROUND(1.525,2)

Answer 1

方法不对，但仍然有效：

CREATE TEMP FUNCTION test(num FLOAT64, decimalPlaces INT64)
RETURNS FLOAT64
LANGUAGE js AS """
    var d = decimalPlaces || 0;
    var m = Math.pow(10, d);
    var n = +(d ? num * m : num).toFixed(8); // Avoid rounding errors
    var i = Math.floor(n), f = n - i;
    var e = 1e-8; // Allow for rounding errors in f
    var r = (f > 0.5 - e && f < 0.5 + e) ?
    ((i % 2 == 0) ? i : i + 1) : Math.round(n);
    return d ? r / m : r;
""";


SELECT ROUND(1.525,2)

Answer 2

有一种更简单的计算方法：

CREATE TEMP FUNCTION bankersRound(num FLOAT64, decimals INT64)
RETURNS FLOAT64
LANGUAGE js AS """
    var scale = Math.pow(10, decimals);
    var result =  value = (Math.round((num * scale) / 2) * 2) / scale;
    return result;
""";

银行家对 BigQuery 的四舍五入

Bankers' rounding for BigQuery

rounding

google-bigquery