Question

我有两个表，property和component。 component.id_property = property.id。

我正在尝试创建一个过程，该过程对所选属性上的组件进行计数，如果所选属性没有组件，则将property.id_state更改为1.

create PROCEDURE property_statement_change AS
BEGIN
declare @value int;

select 
    @value = count(c.value)
from
    component c
where
    c.id_property = 1
group by c.id_property

IF (@value = 0)
  UPDATE property
  SET id_state = 1
  WHERE property.id = 1
END

如果我执行存储的produre，它不会改变任何东西，但是选择并且也可以正确更新。我做错了什么？

Answer 1

如同评论中所述，值为NULL而不是0，所以这里是代码：

create PROCEDURE property_statement_change AS
BEGIN
declare @value int;

select 
    @value = count(c.value)
from
    component c
where
    c.id_property = 1
group by c.id_property

IF (@value is NULL)
  UPDATE property
  SET id_state = 1
  WHERE property.id = 1
END

SQL过程 - 根据其他表的计数更改表列的值

1 个答案: