如何判断sqlite数据库文件是否有效 [英] How to tell if sqlite database file is valid or not

问题描述

在下面的代码中， pathToNonDatabase 是简单文本文件的路径，而不是真正的sqlite数据库。我希望 sqlite3_open 检测到，但它不（ db 不是 NULL 和 result 是 SQLITE_OK ）。那么，如何检测文件不是有效的sqlite数据库？

In the code below, pathToNonDatabase is the path to a simple text file, not a real sqlite database. I was hoping for sqlite3_open to detect that, but it doesn't (db is not NULL, and result is SQLITE_OK). So, how to detect that a file is not a valid sqlite database?

sqlite3 *db = NULL;
int result = sqlite3_open(pathToNonDatabase, &db);

if((NULL==db) || (result!=SQLITE_OK)) { 
   // invalid database
}

推荐答案

sqlite懒惰地打开数据库。

sqlite opens databases lazily. Just do something immediately after opening that requires it to be a database.

最好的可能是 pragma schema_version; 。

• 如果尚未创建数据库，则报告为0（例如，空文件）。在这种情况下，它是安全的工作（和运行 CREATE TABLE 等）


• 如果数据库已创建，模式已经经历了多少修订。


• 如果文件存在且不是数据库（或空），则会收到错误。

• This will report 0 if the database hasn't been created (for instance, an empty file). In this case, it's safe work with (and run CREATE TABLE, etc)
• If the database has been created, it will return how many revisions the schema has gone through. This value might not be interesting, but that it's not zero is.
• If the file exists and isn't a database (or empty), you'll get an error.

如果你想要一个更彻底的检查，你可以使用 pragma quick_check; 。这是一个较轻的完整性检查，它会跳过检查表的内容与索引对齐。它仍然可能很慢。

If you want a somewhat more thorough check, you can use pragma quick_check;. This is a lighter-weight integrity check, which skips checking that the contents of the tables line up with the indexes. It can still be very slow.

避免 integrity_check 。它不仅检查每个页面，而且根据索引验证表的内容。这在大型数据库上是积极的冰川。

Avoid integrity_check. It not only checks every page, but then verifies the contents of the tables against the indexes. This is positively glacial on a large database.

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