SQL定义年间隔多少天？

Question

查询：

SELECT 
      CAST ('2010-12-13' AS TIMESTAMP) - CAST ('2007-01-01' AS TIMESTAMP) <= INTERVAL '4 years',
      CAST ('2010-12-13' AS TIMESTAMP) <= CAST ('2007-01-01' AS TIMESTAMP) + INTERVAL '4 years',
      CAST ('2010-12-13' AS TIMESTAMP) - CAST ('2008-01-01' AS TIMESTAMP) <= INTERVAL '3 years',
      CAST ('2010-12-13' AS TIMESTAMP) <= CAST ('2008-01-01' AS TIMESTAMP) + INTERVAL '3 years'

结果：false true true true

为什么第一列CAST（'2010-12-13'AS TIMESTAMP）-CAST（'2007-01-01'AS TIMESTAMP）<=间隔'4 years'返回FALSE ??

Answer 1

我想我知道了。间隔“ 1年”仅包含360天。

• 第1列：左侧= 1442天，右侧= 360 * 4 = 1440天—>返回false

• 第2列：在右边的表达式中，2007（2007-01-01的年部分）+ 4（4年间隔）= 2011 —>右边=‘2011-01-01’

• 第3列：左= 1077天，右= 360 * 3 = 1080天—>返回true