1. In both databases, there is a table called table_A, that will be confused when performing ORM operations
1. In both databases, there is a table called table_A, that will be confused when performing ORM operations
you can create two MetaData instances that bind different databases engine and associate different Model definitions.
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as shown in the figure below, does SQLAlchemy have a simple way to directly declare that the specified field is not mapped serialized? for example, does java s Hibernate framework have such a function? (although there are other "indirect " solut...
now there is a problem in the project. The project is completed in flask. Now there are several data tables with the same order field, and all need to query the data of these tables and adjust the value of the order field. the inefficient way is to im...
suddenly there is an idea that if the field changes are complicated when making a query, you can t write the query statement, just like A.query.filter (name== ds ) is written dead. If I need to dynamically switch query fields, especially when there ...
Database table mytable structure id id_card INT VARCHAR (32) where id is the self-increasing primary key how to gracefully implement if id_card insertion when it does not exist, of course, thread-safe can not be repeated. my implementation is to a...
problem description I want to execute the SQL script directly to initialize the database when initializing the flask application. the database is Postgresql. the environmental background of the problems and what methods you have tried flask tutor...
The structure of the table is a top-up record table. Users generate a record for each top-up. I want to sum each user s top-up within a period of time, sort it according to the total amount of each user s top-up, and intercept the first few bits. The ...
sqlalchemy operation data Times error: Warning: (1292, "Truncated incorrect DOUBLE value: weixincode ") result = self._query(query) but the data is inserted. Why? the source code is as follows: @staticmethod def create_account(area_c...
whether you use slice or limit offset to do paging, there will be problems as long as you sort and then paginate. Why? there is a problem when PS: only shows that the amount of data per page is less than the total amount of data. Why? result = session...
problem description relationship, with flask sqlalehemy cannot be called. An error message appears TypeError: InstrumentedAttribute object is not callable the environmental background of the problems and what methods you have tried python 3.7...
question I want to query the data of the user signin=0 within a time range in the CarJob_User table. Syntax error: the positional parameter follows the keyword argument. What is wrong with the following code? 2. Code today = datetime.date.tod...
[printed information] after testing the ROLLBACK, execute before self.db.close () in the code session configuration code uses the default: autoflush=True, autocommit=False, expire_on_commit=True [Information queried by yourself] 1. When sqla...