mysql - 用mysql将两列视为一列

Question

我有一张有两次付款的桌子，每张都有自己的日期，如下所示：

table
______________
id
.......
payment1
payment1_date
payment2
payment2_date

我需要的是一个有序的付款清单，忽略它是 payment1 还是 payment2。

付款可以都是空的，只有一个，或两者都填满。

结果如下所示：

id        payments      date         ... 
3         (payment1)    2018-08-01
5         (payment2)    2018-08-03
4         (payment2)    2018-08-04
3         (payment2)    2018-08-07

Payment1 将是预付款，而 payment2 将是其余的，但是对于会计信息，我只想显示按日期排序的所有付款，即该日期 paymentx_date

标签： mysqlsql

Answer 1

我会尝试：

    select id,payment1 as payment, payment1_date as payment_date
    from table
    where payment1 is not null or payment1 <> ''
    union 
    select id,payment2 as payment, payment2_date as payment_date
    from table
    where payment2 is not null or payment2 <> ''
    order by 3