mysql - 想知道sql语句是否正确

Question

所附图像是我的数据库表中的内容。我想计算一个唯一 productSerial 的“IsRead”数量。这里的productSerial 不是主键，所以可以重复。但是我不确定如何为此编写sql语句..

例如，结果应显示为：

10 - 3
11 - 2
12 - 1

我提出了这个，但我想知道它是否正确，如果我错了，希望大家能纠正我。

Select DISTINCT productSerial
  FROM (SELECT COUNT(IsRead) where IsRead = 'True' FROM testing);  

Answer 1

select ProductSerial, count(*)
from testing
where IsRead = 'True'
group by ProductSerial
order by ProductSerial

Answer 2

SELECT ProductSerial, Count(1)
FROM testing
WHERE IsRead = 'True'
GROUP BY ProductSerial
ORDER BY ProductSerial ASC

应该给出相同的结果，并且是一个更简单的查询

Answer 3

不，这是不正确的。您还可以像这样大大简化WHERE子句：

    SELECT DISTINCT productSerial, COUNT(IsRead) FROM testing 
WHERE IsRead = 'True' GROUP BY productSerial

Answer 4

单程：

Select productSerial , COUNT(IsRead) FROM testing where IsRead= 'True' group by productSerial 

Answer 5

怎么样：

select
    ProductSerial,
    Count(IsRead) as Count
from
    testing
where
    IsRead = 'True'
group by
    ProductSerial
order by
    ProductSerial ASC

Answer 6

你可以像下面一样轻松地做

SELECT `ProductSerial` , COUNT( `IsRead` ) AS NumberOfProduct
FROM `table_name`
WHERE `IsRead` = 'True'
GROUP BY `ProductSerial`