选择sqlalchemy中的

Question

我想做这样的事情:

select username, userid, 'user' as new_column  from  users_table.

可以使用sqlalchemy选择表的列,如下所示:

query = select([users_table.c.username, users_table.c.userid])

我该怎么做选择x是col_x在SQLAlchemy的查询？

Answer 1

用这个: users_table.c.userid.label('NewColumn')

即

query = select([users_table.c.username, users_table.c.userid.label('NewColumn')])

评估为:

SELECT username , userid as NewColumn From MyTable;

Answer 2

也许literal_column？

query = select([users_table.c.username, users_table.c.userid, literal_column("user", type_=Unicode).label('new_column')])

参见https://docs.sqlalchemy.org/zh/13/core/sqlelement.html#sqlalchemy.sql.expression.literal_column

编辑：实际上我应该说“文字”：

query = select([users_table.c.username, users_table.c.userid, literal("user", type_=Unicode).label('new_column')])

Answer 3

请参阅alias()此处的文档：https://docs.sqlalchemy.org/en/14/core/selectable.html ?highlight=alias#sqlalchemy.sql.expression.Alias