could not assemble any primary key columns for mapped table

my model:

class Test(db.Model):
    __tablename__ = "Test"  
    STN = db.Column(db.String(3), nullable=False, info='')
    BEG_DATE = db.Column(db.Date, nullable=False, info='')
    END_DATE = db.Column(db.Date, nullable=False, info='')
    PRICE = db.Column(db.String(3), nullable=False, info='')
    REMARK = db.Column(db.String(255), nullable=True, info='')

when I run my flask app, its tips could not assemble any primary key columns for mapped table,Mysql database can create a database without a primary key, Why do I have to set the primary key?I don’t want to set the primary key, how can I solve it?

[zzzeek]

hi there -

please see https://docs.sqlalchemy.org/en/13/faq/ormconfiguration.html#how-do-i-map-a-table-that-has-no-primary-key

if your table has no columns that qualify as a candidate key then it cannot be used by the ORM, you would need to use core only, however, there’s really no such thing in relational databases as a table that doesn’t have a candidate key of some kind, because otherwise it means you can have multiple rows that are complete duplicates of each other, how would that be useful ?

[danerlt]

@zzzeek Thank you for your answer, Eventually I decided to add a primary key to the database table.