我尝试选择两个具有某些公共字段的表.在原始MySQL查询中,我可以这样写：

SELECT t1.id, t1.username, t1.date FROM table1 as 't1' UNION SELECT t2.id, "const_txt", t2.date FROM table2  as 't2'

在该查询中,用户名字段不在table2中,而是设置了const_txt.

因此,在peewee中,我要合并具有相同上述情况的两个表.

class PeeweeBaseModel(Model):
    class Meta:
        database = my_db

class Table1(PeeweeBaseModel):
    id = PrimaryKeyField()
    username = CharField(255)
    date = DateTimeField()
    #other fields ...

class Table2(PeeweeBaseModel):
    id = PrimaryKeyField()
    date = DateTimeField()
    #other fields ...

然后,合并两个模型.像这样的东西：

u = (
    Table1(
        Table1.id,
        Table1.username,
        Table1.date
    ).select() 
    | 
    Table2(
        Table2.id,
        "const_text_instead_real_field_value",
        Table2.date
    ).select()
).select().execute()

但是const_text不会被字段接受,并在结果查询中忽略.

问题是：如何定义表中不存在的字段并在查询中手动设置它？

(而且我更喜欢不使用SQL()函数.)

谢谢.

解决方法:

您可以在SELECT语句中使用SQL().

u = (
    Table1(
        Table1.id,
        Table1.username,
        Table1.date
    ).select() 
    | 
    Table2(
        Table2.id,
        SQL(" '' AS username "),
        Table2.date
    ).select()
).select().execute()