Question

我试图用另一个表中某个条件为真的值覆盖一个字段值。我在下面模拟了我的代码

伪代码：

upstream mydjangoback {
       server 127.0.0.1:8000;
       server 127.0.0.1:8001;
       server 127.0.0.1:8002;
}

server {
        listen 80;

        location = /favicon.ico { access_log off; log_not_found off; }
        root /home/raka/djwsgi;
        server_name  mydjango.com;

        location /static/ {
            root /home/raka/djwsgi;
        }

        location / {
            proxy_pass http://mydjangoback;
        }
    }

我的代码：

Where an employee has the team Ops in old_data, get their new team from new_data and overwrite the team in old_data

但这会返回错误：

UPDATE old_data -- This has columns Employee, Latest_Team
SET
    Latest_Team = 
           (select new_data.team
            from new_data
            left join old data
            ON old_data.employee = new_data.employee
           )
WHERE old_data.employee = 'Ops'

我不确定我到底要去哪里

Answer 1

确保此查询不返回任何内容，并且您的代码可以正常工作

select new_data.team, count(*)
            from new_data
            left join old data WHERE old_data.employee = 'Ops'
group by new_data.team
having count(*) > 1

如果每个员工的Old_data.employee ='Ops'有多个团队，则sql不会知道为该员工选择哪个进行更新

Answer 2

您的联接中有错字-“旧数据”应为“ old_data”。

也许这可以帮助您：update columns values with column of another table based on condition

在您的示例中为：

UPDATE old_data SET
    Latest_Team = (SELECT new_data.team FROM new_data WHERE old_data.employee = new_data.employee LIMIT 1)
    WHERE old_data.employee = 'Ops';

Answer 3

如果您正在寻找 team “ ops”，那么您的查询有几个问题：

您要过滤的是员工，而不是团队。
内部from子句中有错字。
您想要一个相关的子查询。

所以，我想你想要

UPDATE old_data -- This has columns Employee, Latest_Team
    SET Latest_Team = (select nd.team
                       from new_data nd
                       where old_data.employee = nd.employee
           )
WHERE od.latest_team = 'Ops';
------^  I think this is the filter you describe

在满足以下条件的情况下更新行

3 个答案: