仅使用子选择的Oracle查询

Question

我只想返回包含三列的1行

(SELECT count(1) from tests) TestCount, 
(select count(1) from customers) CustomerCount, 
(select count(1) from patients) PatientCount

Answer 1

请尝试：

select 
  (SELECT count(1) from tests) TestCount, 
  (select count(1) from customers) CustomerCount, 
  (select count(1) from patients) PatientCount
from dual;

Answer 2

SELECT  TestCount.TestCount,
        CustomerCount.CustomerCount,
        PatientCount.PatientCount
FROM    (SELECT count(1) TestCount from tests) TestCount
        CROSS JOIN
        (select count(1) CustomerCount from customers) CustomerCount
        CROSS JOIN
        (select count(1) PatientCount from patients) PatientCount