php - 获取具有值的列的百分比

Question

我试着这样做:

 SELECT (SELECT COUNT(*)
 FROM users WHERE email != '') / (SELECT COUNT(*) FROM users)

但它在 php Operand should contain 1 column(s) 中给了我这个错误，在 mysql 中一切正常。还有其他解决方案吗？

EDIT : its not exactly like that I had also groups by months, the above query works but the accepted answer solves my error

Answer 1

您可以在单个查询中完成:

SELECT SUM(email != '') / COUNT(*) 
    AS ratio
  FROM users

...或者，如果您需要百分比:

SELECT 100 * SUM(email != '') / COUNT(*)
    AS percentage
  FROM users