Question

我正在尝试按时间间隔计算观看次数。以下请求仅在没有AND子句的情况下有效

如果我取出AND s.timestamp < 2019-01-31，它就可以正常工作。

SELECT s.category_id, c.name, count(s.category_id) AS ViewCount 
FROM stat_product_category s 
JOIN category c ON s.category_id = c.id 
WHERE s.timestamp > 2019-01-01 AND s.timestamp < 2019-01-31
GROUP BY s.category_id 
ORDER By ViewCount Desc 
LIMIT 10

Answer 1

您需要在日期值上加上单引号

SELECT s.category_id, c.name, count(s.category_id) AS ViewCount 
FROM stat_product_category s 
JOIN category c ON s.category_id = c.id 
WHERE s.timestamp > '2019-01-01' AND s.timestamp <'2019-01-31'
GROUP BY s.category_id ,c.name
ORDER By ViewCount Desc 
LIMIT 10

Answer 2

那些不是时间戳-没有引号，您只需要减去几个整数即可。将2019-01-01评估为2019-1-1或2017.将2019-01-31评估为2019-1-31或1987.没有大于2017的数字但小于1987的数字，因此得到没有结果。这些值用引号引起来将使它们成为字符串文字，并允许数据库执行隐式转换为日期：

SELECT s.category_id, c.name, count(s.category_id) AS ViewCount 
FROM stat_product_category s 
JOIN category c ON s.category_id = c.id 
WHERE s.timestamp > '2019-01-01' AND s.timestamp < '2019-01-31'
-- Here ------------^----------^-------------------^----------^
GROUP BY s.category_id 
ORDER By ViewCount Desc 
LIMIT 10

Answer 3

该脚本看起来不错，您只需要在日期周围弹出qoutes即可，以便SQL知道值在何处开始和结束。

SELECT s.category_id, c.name, count(s.category_id) AS ViewCount 
FROM stat_product_category s 
JOIN category c ON s.category_id = c.id 
WHERE s.timestamp > '2019-01-01' AND s.timestamp < '2019-01-31'
GROUP BY s.category_id 
ORDER By ViewCount Desc 
LIMIT 10

（经测试可正常工作！）

项目进展顺利！

SQL日期间隔不适用于AND子句

3 个答案: