Unverified50% confidenceFactExact time
PostgreSQL的聚合函数会忽略NULL值：COUNT(*)统计所有行，COUNT(val)、SUM、AVG忽略NULL值
1
Sources
50%
Confidence
Long-term
Relevance
9/12/2026
First Seen
Sources
Related Entities
Related Claims
UnverifiedPostgreSQL默认将NULL视为最大值，升序排序中排在末尾，降序中排在开头74% similarUnverified在PostgreSQL中，SELECT NULL = NULL 返回NULL而不是TRUE73% similarUnverifiedDECIMAL与NUMERIC在标准SQL中语义等价，均通过十进制精确存储数字，避免FLOAT/DOUBLE二进制浮点表示的舍入误差68% similarUnverified在一对多关系中用错JOIN键会产生行数膨胀，使SUM聚合结果成倍增长，而SQL不会抛出任何异常63% similarUnverified对于 PostgreSQL，分区总数建议不超过1000个63% similar
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