如何通过Python在PostGreSQL中插入列注释？ [英] How can I insert column comments in PostGreSQL via Python?

问题描述

我想为PostGreSQL数据库中Python的许多列添加注释。
如果我运行我的Python脚本在数据库客户端中手动生成的语句，则一切正常。
如果我让Python通过sqlalchemy引擎运行该语句，则不会更新任何内容。

I want to add a comment to a number of columns from Python in a PostGreSQL database. If I run the statement that my Python script produces in a database client manually everything works as it should. If I let Python run the statement via an sqlalchemy engine, nothing is updated.

我在Python中有一个格式为 {'column name'：'column comment with some text'} 的字典。

I have a dictionary in Python of the form { 'column name': 'column comment with some text'}.

我想将此注释添加到PostGres数据库中的现有表中。

I want to add this comments to an existing table in a PostGres database.

手动地，我将在PostGres中运行以下命令：

Manually I would run the following command in PostGres:

comment on column schema.table."column name" is 'column comment with some text'

现在在Python中，我想运行相同的命令，但随后遍历字典。这是我使用的代码：

Now in Python I want to run the same, but then looping over the dictionary. This is the code I use:

from sqlalchemy import create_engine, text

db = create_engine(f"postgresql://PGUSER:PGPASSWORD@PGHOST/PGDATABASE")

coldict = {'col1': 'col1 contains this data, etc... some more comments', 'col2': 'col2 shows something.'}

with db.connect() as con:
        for key in coldict:
            colname = key
            # Convert a single quote to two single quotes as that is what SQL likes.
            colcomm = coldict[key].translate(str.maketrans({"'": "''"}))
            stmt = f"comment on column schema.table.\"{colname}\" is '{colcomm}';"
            # print the statement that will be run for debugging
            print(stmt)
            # execute statement in database
            con.execute(text(stmt))

打印输出：

comment on column schema.table."col1" is 'col1 contains this data, etc... some more comments';
comment on column schema.table."col2" is 'col2 shows something.';

当我使用此答案实际未设置任何注释。

When I check the column comments with the query from this answer no comments are actually set.

如果我将复制粘贴的内容打印到数据库客户端中，

If I copy-paste what is printed out into a database client and run it there, the column comment is updated as it should.

如何通过Python中的循环更新列注释？

How can I update the column comment via a loop in Python?

推荐答案

您尚未提交更改，因此它们会自动回滚。一种方法是：

You did not commit your changes, so they are automatically rolled back. One way to do it is:

con.execute(text(stmt).execution_options(autocommit=True))

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