sql - 显示来自另一个表

Question

我有一个里程碑表：

和状态表：

我有一个问题：

SELECT T1.Status,T2.MilestoneTitle FROM [Organisation].[dbo].[Status] T1
JOIN [Organisation].[dbo].[Milestone] T2 
ON T1.StatusId=T2.MilestoneStatusId WHERE T2.ProjectId=4

，输出为：

现在，我想将输出显示为：

如何为此编写查询？

Answer 1

通过使用Count和Group，我们可以实现这个目标

SELECT 
    T1.Status, COUNT(T2.MilestoneTitle) AS MilestoneTitleCount  
FROM 
    [Organisation].[dbo].[Status] T1
JOIN 
    [Organisation].[dbo].[Milestone] T2 ON T1.StatusId  = T2.MilestoneStatusId 
WHERE 
    T2.ProjectId = 4
GROUP BY 
    T1.Status
ORDER BY   
    T1.Status DESC

Answer 2

SELECT Status, COUNT(MilestoneTitle) AS MilestoneTitleCount
FROM Organisation.dbo.Status  INNER JOIN
Organisation.dbo.Milestone  ON StatusId = MilestoneStatusId
WHERE (ProjectId = 4)
GROUP BY Status

COUNT()函数返回符合指定条件的行数。

SELECT COUNT(column_name) FROM table_name;

GROUP BY语句与聚合函数结合使用，可以按一列或多列对结果集进行分组。

SELECT column_name, Count(column_name)
FROM table_name
WHERE <Confidtion>
GROUP BY column_name;