Question

场景是我在表中有一个名为“States”的列，状态可以是0,1,2,3或4.我想要做的是使用WHERE State =计算每个州的状态单个查询。

主要目的是我想显示记录的数量（由他们的州确定）。像这样， 20条记录的状态为0 等。

这可能吗？如果是，那我该如何实现呢？

编辑：我知道Count。这是我尝试过的：

SELECT State, Date_Created, (SELECT COUNT(Id) FROM [ECOS].[eco].[tb_projects_details] WHERE State=1) as State_One, (SELECT COUNT(Id) FROM [ECOS].[eco].[tb_projects_details] WHERE State=2) as State_Two, (SELECT COUNT(Id) FROM [ECOS].[eco].[tb_projects_details] WHERE State=0) as State_Zero, (SELECT COUNT(Id) FROM [ECOS].[eco].[tb_projects_details] WHERE State=4) as State_Four FROM [ECOS].[eco].[tb_projects_details] WHERE Date_Created < dateadd(week,-3,getdate());

Answer 1

要生成值列表及其计数，您可以执行以下操作：

SELECT State, COUNT(*) AS C
FROM mytable
GROUP BY State

要生成一行包含值计数作为列的行，您可以执行以下操作：

SELECT
COUNT(CASE State WHEN 0 THEN 1 ELSE NULL END) AS State_0_Count,
COUNT(CASE State WHEN 1 THEN 1 ELSE NULL END) AS State_1_Count,
COUNT(CASE State WHEN 2 THEN 1 ELSE NULL END) AS State_2_Count,
COUNT(CASE State WHEN 3 THEN 1 ELSE NULL END) AS State_3_Count,
COUNT(CASE State WHEN 4 THEN 1 ELSE NULL END) AS State_4_Count
FROM [...]
WHERE [...]

Answer 2

如果我理解正确，你想分组并计算：

SELECT   mt.States, COUNT(*) total
FROM     my_table mt
GROUP BY mt.States

Answer 3

如果在group by条件之后使用where子句，那将非常容易。然后，您将很容易得到每个州的数量。

SELECT state, count(*)
FROM table_name 
GROUP BY state

Answer 4

下次首先阅读sql for beginners book。

Select state, count(*)
from table 
group by state

在“选择查询”中使用不同条件计数

4 个答案: