在SQL中执行多列的COUNTS DISTINCT的SUM

Question

COUNT(DISTINCT invoiceType1)` AS `#invoices2`, 
COUNT(DISTINCT invoiceType2)` AS `#invoices2`, 

有没有办法将这两个计数加在一起？虽然它们都是DISTINCT但我不确定它是否会表现正常。

谢谢。

Answer 1

试试这个，只需使用'+'运算符

添加这两个计数

SELECT
COUNT(DISTINCT invoiceType1) AS #invoices1, 
COUNT(DISTINCT invoiceType2) AS #invoices2, 
COUNT(DISTINCT invoiceType1) + COUNT(DISTINCT invoiceType2) AS #totalinvoicescount
FROM tablename