Question

如何计算位于同一个表中的两组数据之间的添加，删除和修改？这是一个例子：

drop table if exists people;
create table people (job int, id int, name varchar(255));

insert into people values (1, 1, "Amy");
insert into people values (1, 2, "Bob");
insert into people values (1, 3, "Chris");

insert into people values (2, 1, "Amy");
insert into people values (2, 2, "Robert");
insert into people values (2, 4, "Dennis");

在这个例子中，Bob的名字已经改为Robert，Chris已被删除，Dennis已被添加。

到目前为止，我可以得到补充：

select p2.* from people p1
right join people p2
on p1.job = 1
and p2.job = 2
and p1.id = p2.id
where p2.job = 2
and p1.id is null;

我可以得到删除：

select p1.* from people p1
left join people p2
on p1.job = 1
and p2.job = 2
and p1.id = p2.id
where p1.job = 1
and p2.id is null;

但我不确定如何进行修改。

有更好的方法吗？

由于

Answer 1

对于示例数据，这将返回已修改的：

select * from people p1
join people p2
on p1.job = 1 
and p2.job = 2
and p1.id = p2.id         -- same id
WHERE p1.name <> p2.name  -- but different name

Answer 2

我设法搞清楚了！

select * from people p1
join people p2
on p1.job = 1
and p2.job = 2
and p1.id = p2.id
where p1.name != p2.name;

最终它并不是那么糟糕。

计算单个表的增量

2 个答案: