想知道sql语句是否正确

Question

附图是我在数据库表中的内容。我希望计算出对于独特的productSerial而言属于“IsRead”的数量。这里的productSerial不是主键，因此可以重复。但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

我出来了，但我想知道这是否正确，并希望如果我错了，你们都可以纠正我。

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，这不正确。您还可以大大简化 WHERE 子句，如下所示：

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

Answer 4

一种方式：

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

你可以轻松地像以下一样

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