This error occurs when trying to reuse a prepared SQLite statement that has already been finalized (closed). It typically happens after database connection closure or when the statement object is garbage collected while code still holds a reference to it.
The better-sqlite3 library wraps SQLite prepared statements, and each statement is implicitly finalized once its database connection closes or the statement object is garbage collected. Once `sqlite3_finalize()` runs, the SQLite handle becomes invalid and any subsequent call raises "This statement has already been finalized." This is a safety mechanism to prevent use-after-free errors in the SQLite engine.
Keep your database connection alive until every prepared statement has completed execution. Call db.close() only as the final step after all queries are done. If you need to run queries after closing, reopen the database and prepare fresh statements.
If using statements in async callbacks or timeouts, store references in a higher scope to prevent garbage collection. Dropping the last reference allows the garbage collector to finalize the statement, causing errors on subsequent access.
When you need to execute the same SQL repeatedly, call db.prepare() to create a new statement rather than reusing a finalized one. You can also use stmt.reset() and stmt.bind() for repeated executions with the same prepared statement.
Be aware that some transaction patterns may implicitly finalize statements. Ensure statements used within transactions are not accessed after the transaction completes unless they were prepared outside the transaction scope.
SQLite strictly prohibits reuse of finalized statement handles. The SQLite C API documentation states that applications must not call any SQLite functions on a statement after sqlite3_finalize() completes. better-sqlite3 automatically finalizes statements when connections close or when statement objects are garbage collected, aligning with SQLite's safety requirements.
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