Sqlite：如何将多个表更新拆分为多个语句

Question

Sqlite 更新不支持连接。对于以下示例，

update Employee t0 LEFT join EmployeeDetail t1 on (t1.id=t0.id) 
set t0.status=1, t1.salary=t1.salary+10000
where t1.salary < 50000 and t0.status=0

要更新的列属于不同的表，它们在哪里 条款。如果使用子查询拆分成如下两条语句：

update Employee set status=1
where id in (select t0.id from
Employee t0 LEFT join EmployeeDetail t1 on (t1.id=t0.id) 
where t1.salary < 50000 and t0.status=0)

update EmployeeDetail set salary=salary+10000
where id in (select t1.id from
Employee t0 LEFT join EmployeeDetail t1 on (t1.id=t0.id) 
where t1.salary < 50000 and t0.status=0)

执行一个语句会影响另一个语句，因为它会影响 where 子句 限制。

Sqlite 数据库如何解决这个问题？

Answer 1

我建议将要更新的 id 存储在临时表中，然后使用它。这还可以防止竞争条件并简化锁定。

create temporary table ids as 
    select e.id
    from Employee e join
         EmployeeDetail ed
         on e.id = ed.id
where ed.salary < 50000 and e.status = 0;

然后简单地做：

update employee e
    set status = 1
    where id in (select id from ids);

update employeedetail
    set salary = salary + 10000
    where id in (select id from ids);