检查Count的结果是否等于零Oracle

Question

我需要在两个相似的表之间执行MINUS操作，对结果行进行计数，并检查SQL语句中所有计数是否等于零。

我已经完成了以下工作，但是我不确定如何将其与零进行比较。

select count(*) from(select * from table1 MINUS SELECT * FROM table2)

Answer 1

像这样吗？

SQL> with t_minus as
  2    (select deptno from emp
  3     minus
  4     select deptno from dept
  5    )
  6  select case when count(*) = 0 then 'it is zero'
  7              else 'it is not zero'
  8         end result
  9  from t_minus;

RESULT
--------------
it is zero

---

SQL> with t_minus as
  2    (select empno from emp
  3     minus
  4     select deptno from dept
  5    )
  6  select case when count(*) = 0 then 'it is zero'
  7              else 'it is not zero'
  8         end result
  9  from t_minus;

RESULT
--------------
it is not zero

SQL>