How to execute VACUUM command on SQLITE db

[Marmelade]

Hello,

I can't run VACUUM on my database file.

I tried this:

QSqlQuery query;
query.exec("VACUUM");

QSqlQuery query;
query.exec("VACUUM");

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But I get the following message:

cannot VACUUM - SQL statements in progress Unable to fetch row

cannot VACUUM - SQL statements in progress Unable to fetch row

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Do you have an idea to solve this problem?

Thanks