Check for multiple statements in prepare

[thomcc]

Consider checking by default if someone does something like conn.prepare("<stmt 1>; <stmt 2>"). This will silently only run stmt 1, which is probably not what the user wants.

Right now, I believe we have some tail checking here, but I think it's only under extra-check feature. It also might be disabled then too. I think we should probably check this always, since I don't see a case where anybody wouldn't want this detected.

[gwenn]

You may have false positive with some trailing comments "SELECT 1; /comments/;"

[thomcc]

Yeah. I think that's probably fine.

[jvasile]

I ran into this issue in my own code and worked up a crate to quickly split strings containing multiple sqlite statements and also to tell me when I'm dealing with multiple sql statements. It's standalone functionality, so I put it in its own crate, but I could easily turn it into a PR.

sql_split is O(n) to split, where n is the length of the string. It also has a short-circuiting func, is_multiple, that just tells you if you're dealing with a multi-statement string.

If this is useful to rusqlite, I'd be happy to turn it into a PR.

[gwenn]

• https://sqlite.org/lang_createtrigger.html and statements between BEGIN and END => you cannot split easily
• https://sqlite.org/lang_createvtab.html and module arguments which can be anything (CREATE VIRTUAL TABLE my_csv USING csv(filename=..., delimiter=;);)

[thomcc]

I think we should take the current approach, where we used the tail returned by SQLite. This has downsides, but is much less error-prone than trying to parse it ourselves IMO.

[jvasile]

Yes, that's right. I thought it could be done simply, but after chasing down a bunch of edge cases and handling virtual tables, I think this "simple" bit of code will quickly get hairier than its worth.

[d-bucur]

Would also be great if there was an equivalent method for multiple statements, like there is for execute_batch. The only way to do that currently is to manually format the string and send it to execute_batch

[gwenn]

We should be able to check at compile time that only a single statement is provided with sqlite3-parser if the SQL is a static string.

[gwenn]

There is a new single! macro here.
But it cannot be used inside rusqlite existing method.
For example, it cannot work if put inside Connection::execute method.
I can work only if used like this:

let changes = conn.execute(single!("DELETE FROM my_table WHERE col = ?"), ...)?;

which is not user-friendly...
Do you know how to make it nicer (without duplicating rusqlite public API) ?

Edit: I am going to try conditional attribute-like macro => doesn't work

    #[inline]
    #[cfg_attr(feature = "rusqlite-macros", single())]
    pub fn execute<P: Params>(&self, sql: &str, params: P) -> Result<usize> {