Oracle数据库使用短路评估。也就是说，对于一个简单的CASE表达式，数据库仅在将每个compare_expr值与expr进行比较之前才对其求值，而不是在将任何一个compare_expr值与expr进行比较之前才求值。因此，如果先前的compare_expr等于expr，则Oracle永远不会评估comparison_expr。对于搜索的CASE表达式，数据库将评估每个条件以确定其是否为真，并且如果先前的条件为真，则从不评估条件。
但是下面的SQL正在返回divisor is equal to zero：
WITH data AS (SELECT 1 AS cond, 10 AS num, 0 AS div FROM DUAL)
SELECT
CASE WHEN cond = 2 THEN (CASE WHEN MAX(div) = 0 THEN 0 ELSE SUM(num / div) END)
ELSE -1
END AS result
FROM data
GROUP BY cond
有什么办法可以避免divisor is equal to zero错误？
编辑
此查询工作正常：
WITH data AS (SELECT 1 AS cond, 10 AS num, 0 AS div FROM DUAL)
SELECT
CASE WHEN cond = 2 THEN (CASE WHEN MAX(div) = 0 THEN 0 ELSE 1 END)
ELSE -1
END AS result
FROM data
GROUP BY cond
用
CASE WHEN cond = 2
THEN SUM(case when div = 0 then 0 else num / div end)
ELSE -1
END
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