How to Effectively Execute Raw SQL Queries in Flask-SQLAlchemy?

Execute raw SQL in Flask-SQLAlchemy application

In Flask-SQLAlchemy, when dealing with complex data operations that cannot be achieved using SQLAlchemy ORM, raw SQL queries need to be executed. This article explores ways to efficiently execute raw SQL in Flask-SQLAlchemy applications.

Method:

The preferred way to execute raw SQL in SQLAlchemy is to establish a direct database connection. Using this connection, you can execute arbitrary SQL statements without being restricted by the ORM.

SQLAlchemy 2.0:

For SQLAlchemy 2.0, the recommended approach is to use the engine.connect() context manager to create temporary database connections. In this context you can execute raw SQL queries.

with engine.connect() as connection:
    result = connection.execute(text('SELECT * FROM your_table'))
    # 处理查询结果

SQLAlchemy 1.x:

In SQLAlchemy 1.x, you can use the db.engine.execute() method to directly execute raw SQL queries. However, it is important to note that this method is "connectionless" and has been deprecated in later versions of SQLAlchemy.

from sqlalchemy import text

sql = text('select name from penguins')
result = db.engine.execute(sql)
names = [row[0] for row in result]

Summary:

By using the above techniques, you can seamlessly execute raw SQL queries in your Flask-SQLAlchemy application. Remember to establish a database connection for each raw SQL operation and handle the results appropriately.

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