MySQL：计算结果组

Question

我有一张看起来有点像这样的表：

ID
word
timestamp

现在我需要一个看起来像这样的结果：

word (unique)
total number of records for this word
total number of records for this word between date1 and date 2
total number of records for this word between date2 and date 3

即：我需要所有（唯一）单词的列表（我可以通过GROUP BY子句实现）和各个时段的计数。

虽然我知道如何通过多个查询和一些PHP实现这一点，但我想知道是否可以创建一个（因此更高性能）表。

有人可以帮助我吗？

Answer 1

是的，而不是计算你的求和，因为布尔表达式返回true或false，这与1或0相同。

SELECT
word,
COUNT(*) AS 'total number of records for this word',
SUM(timestamp BETWEEN $date1 AND $date2) AS 'total number of records for this word between date1 and date 2',
SUM(timestamp BETWEEN $date2 AND $date3) AS 'total number of records for this word between date2 and date 3'
FROM your_table
GROUP BY word;