SQL:单个查询中有两个计数函数？

Question

如何将这两个计数函数放入一个查询中？

SELECT 
    COUNT(MaritalStatus) as 'Married'
FROM 
    Person.Person PP 
INNER JOIN 
    HumanResources.Employee HRE ON PP.BusinessEntityID = HRE.BusinessEntityID
WHERE 
    MaritalStatus = 'M';

SELECT 
    COUNT(MaritalStatus) as 'Single'
FROM 
    Person.Person PP 
INNER JOIN 
    HumanResources.Employee HRE ON PP.BusinessEntityID = HRE.BusinessEntityID
WHERE 
    MaritalStatus = 'S';

Answer 1

您可以在以下情况下尝试使用总和大小写:

SELECT SUM(CASE WHEN MaritalStatus = 'M' THEN 1 ELSE 0 END), 
SUM(CASE WHEN MaritalStatus = 'S' THEN 1 ELSE 0 END) 
FROM Person.Person PP INNER JOIN HumanResources.Employee HRE
ON PP.BusinessEntityID = HRE.BusinessEntityID