Question

我使用了一个视图来获得正确的答案，但是我想在一个SQL语句中使用它，我也想知道是否有办法在不重新抛出表格的情况下进行操作。

我可以COUNT(OW_OWNERNO) AS NO_HOUSES在我的where子句中使用NO_HOUSES吗？有没有办法定义它。

本声明试图计算数据库中人员拥有的房屋数量，并仅计划拥有多个房屋的人。

CREATE VIEW NUMHOUSE AS
SELECT OW_FIRSTNAME, OW_LASTNAME, **COUNT(OW_OWNERNO) AS NO_HOUSES**
FROM (rentproperty JOIN OWNER ON RP_OW_OWNERNO = OW_OWNERNO)
WHERE RP_TYPE = 'House'
GROUP BY OW_OWNERNO;

SELECT * FROM NUMHOUSE

NO_HOUSES＆gt; 1;

Answer 1

这有两种方法。第一个使用Fabio建议的having子句。

SELECT OW_FIRSTNAME, OW_LASTNAME, COUNT(OW_OWNERNO) AS NO_HOUSES
FROM (rentproperty JOIN OWNER ON RP_OW_OWNERNO = OW_OWNERNO)
WHERE RP_TYPE = 'House'
GROUP BY OW_OWNERNO
having no_houses > 1  -- note some dbs might not let you use an alias here

这个使用子查询

select * from (
SELECT OW_FIRSTNAME, OW_LASTNAME, COUNT(OW_OWNERNO) AS NO_HOUSES
FROM (rentproperty JOIN OWNER ON RP_OW_OWNERNO = OW_OWNERNO)
WHERE RP_TYPE = 'House'
GROUP BY OW_OWNERNO
) temp
where no_houses > 1

他们同样运作良好。

Answer 2

我认为您应该使用HAVING代替WHERE

实施例

SELECT * FROM NUMHOUSE HAVING COUNT(NO_HOUSES) > 1;

我需要使用我在Select语句中创建的临时属性才能在Where语句中使用它？

2 个答案: