Question

我尝试了一些子查询，但我没有成功。

假设我们有2个表：用户（iduser，名称），发票（idinvoice，title，status，iduser）我们希望为每个用户显示总发票“已付款”，总发票“未付”（即状态字段）

我尝试过这样的查询

Select users.*, total_invoices_paid, total_invoices_unpaid
from users
LEFT JOIN (SELECT iduser, sum(if(status='paid',1,0)) AS total_invoices_paid, sum(if(status='unpaid',0,1)) AS total_invoices_unpaid 
           FROM invoices GROUP BY invoices.idinvoice) AS subinvoices
ON subinvoices.iduser=users.iduser

但我错了价值观，我觉得我错过了什么，但不知道是什么

有什么帮助吗？

由于

Answer 1

我想你想要这个：

select u.*,
    sum(i.status = 'paid') as total_invoices_paid,
    sum(i.status = 'unpaid') as total_invoices_unpaid
from users u
left join invoices i on u.iduser = i.iduser
group by u.iduser;

在MySQL中，boolean分别被计算为1或0表示true或false。因此，在条件上使用sum，我们可以找到计数。

使用子查询：

select u.*,
    coalesce(i.total_invoices_paid, 0) as total_invoices_paid,
    coalesce(i.total_invoices_unpaid, 0) as total_invoices_unpaid,
    coalesce(i.total_invoices, 0) as total_invoices,
    coalesce(i.total_paid_and_unpaid, 0) as total_paid_and_unpaid,
    coalesce(i.total_with_non_null_status, 0) as total_with_non_null_status
from users u
left join (
    select iduser,
        sum(status = 'paid') as total_invoices_paid,
        sum(status = 'unpaid') as total_invoices_unpaid,
        count(1) as total_invoices,
        sum(status in ('paid','unpaid')) as total_paid_and_unpaid,
        count(status) as total_with_non_null_status
    from invoices
    group by iduser
    ) i on u.iduser = i.iduser
group by u.iduser;

mysql子查询总共在2个表之间

1 个答案: