将一个count（）除以另一个

Question

尝试通过将IsComplete = 1的行数除以行总数来从SQL查询中获取百分比值。我怎样才能做到这一点？

数据库表：

Answer 1

由于值始终为0或1，您可以将值相加并除以计数，如：

SELECT SUM(IsComplete) / COUNT(*) AS percent_complete FROM centraldb.project;

如果您愿意，则乘以100。

Answer 2

由于在聚合函数中不使用null，请尝试：

select count(case when isComplete = 1 then isComplete end) / count(*)
  from project

Answer 3

SELECT sum(case when isComplete =1 then 1 else 0)/
       count(*)*100  as percentComplete
FROM project

Answer 4

这应该

SELECT ((SELECT COUNT(*) FROM centraldb WHERE IsComplete = 1) / COUNT(*)) AS percentage FROM centraldb;

For example