![]() ![]() I see QSqlQuery::finish() which there's normally no need to call it. Looking at the docs for QSqlQuery, I see QSqlQuery::clear() with the statement that I should rarely if ever need it. Further, there are some querys hanging around and that means memory leaks! I read that message to mean that the database is closed but that I still have a connection to it somewhere. STEP 1) DUMMY DATABASE 1A) USERS TABLE S1Ausers. When I run the program, and close it, after the debug messages showing the database is closed, I get an error message stating : QSqlDatabasePrivate::removeDatabase: connection 'qt_sql_default_connection' is still in use, all queries will cease to work. The End SQLITE DATABASE TO HTML TABLE All right, let us now walk through the steps of displaying an HTML table from an SQLite database. In various functions in the program, I create a QSqlQuery, but these are created within the function and should, as I understand it, go away or become non-existant when the function ends. It also seems to work, based on the debug couts in place. ![]() However, because double-clicking starts the sqlite3.exe without command-line arguments, no database file will have been specified, so SQLite will use a temporary database that is deleted when the session exits. ![]() Std::cout << "the database is: Closed" << std::endl ĭb.removeDatabase( QSqlDatabase::defaultConnection ) Windows users can double-click on the sqlite3.exe icon to cause the command-line shell to pop-up a terminal window running SQLite. This is optional - you could just use external files, but this way you get to ship them all wrapped-up nice and cosy in the database itself. Std::cout << "the database is: open" << std::endl Open up your DB and store them in the sqlar table. In the function I call to quit the program is a call to this function: /QSqlError closeDb() If the same database file has been attached with multiple aliases, then DETACH command will disconnect only the given name and rest of the attachment will still continue. I guess I'm a little confused.I have a function in my program that creates or opens a SqLite database: QSqlError createDb()ĭb = QSqlDatabase::addDatabase("QSQLITE") SQLite DETACH DATABASE statement is used to detach and dissociate a named database from a database connection which was previously attached using ATTACH statement. So is there a difference between Close() and null on a DB connection? Otherwise, while would you check for != null or = null. So, as far as I understand I can: 1) Read db from multiple threads ( SELECT ) 2) Read db from multiple threads ( SELECT) and write from single thread ( CREATE, INSERT, DELETE) But, I read about Write-Ahead Logging that provides more concurrency as readers do not block writers and a writer does not block readers. The problem I'm facing is that all my methods connect this same exact way with only the 'conn = null' check without issue but this one method code returns 'database is closed'. The SQLite project provides a simple command-line program named sqlite3 (or sqlite3. Use the interrupt character (usually a Ctrl + C) to stop a long-running SQL statement. So I added the 'conn.isClosed' and it worked. You can terminate the SQLite 3 program by typing your system's end-of-file character (usually a Ctrl + D). ![]() Initially, I was checking for 'conn = null' only, which most examples do. Public static Connection getConnection() throws SQLExceptionI also discovered while testing the following code that it returns an SQLException "database not connected" even though I'm checking for it. Private static final String SQLhome = "jdbc:sqlite:" + GlobalVariables.ResearchDB_PATH Code: import researchApp.GlobalVariables ![]()
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