在Python程序中使用SQLite [英] Using SQLite in a Python program

问题描述

我已经创建了一个Python模块来创建和填充几个SQLite表。现在，我想在一个程序中使用它，但我真的不知道如何正确地调用它。我发现的所有教程本质上都是内联，即他们以线性方式走过SQLite，而不是如何在生产中实际使用它。

尝试做的是进行方法检查以查看数据库是否已经创建。如果是这样，那么我可以使用它。如果没有，则引发异常，程序将创建数据库。 （或使用if / else语句，以较大者为准）。

我创建了一个测试脚本来查看我的逻辑是否正确，但它不工作。当我创建try语句时，它只创建一个新的数据库，而不是检查是否已经存在。下次运行脚本时，即使我尝试捕获异常，我也收到了表已经存在的错误。 （我没有使用过/除了以前，但认为这是一个很好的学习时间）。

有没有任何好的教程使用SQLite操作或任何建议如何编码这个？我已经看过pysqlite教程和其他我发现但他们没有解决这个问题。

解决方案

AFAIK一个SQLite数据库是只是一个文件。
要检查数据库是否存在，请检查文件是否存在。

当您打开SQLITE数据库时，如果备份的文件为

如果您尝试打开一个不是数据库的sqlite3数据库的文件，您将获得以下信息：

sqlite3.DatabaseError：文件被加密或不是数据库

所以检查文件是否存在，还要确保尝试如果文件不是sqlite3数据库

，则捕获异常

I have created a Python module that creates and populates several SQLite tables. Now, I want to use it in a program but I don't really know how to call it properly. All the tutorials I've found are essentially "inline", i.e. they walk through using SQLite in a linear fashion rather than how to actually use it in production.

What I'm trying to do is have a method check to see if the database is already created. If so, then I can use it. If not, an exception is raised and the program will create the database. (Or use if/else statements, whichever is better).

I created a test script to see if my logic is correct but it's not working. When I create the try statement, it just creates a new database rather than checking if one already exists. The next time I run the script, I get an error that the table already exists, even if I tried catching the exception. (I haven't used try/except before but figured this is a good time to learn).

Are there any good tutorials for using SQLite operationally or any suggestions on how to code this? I've looked through the pysqlite tutorial and others I found but they don't address this.

解决方案

AFAIK an SQLITE database is just a file. To check if the database exists, check for file existence.

When you open a SQLITE database it will automatically create one if the file that backs it up is not in place.

If you try and open a file as a sqlite3 database that is NOT a database, you will get this:

"sqlite3.DatabaseError: file is encrypted or is not a database"

so check to see if the file exists and also make sure to try and catch the exception in case the file is not a sqlite3 database

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