Improve handling of SQLite savepoints (sqlitebrowser#878) (sqlitebrow…

…ser#836)

Previously all savepoints were added to and deleted from
`savepointList`, so some savepoints could not be released, which lead to
warnings and errors, e.g. it was impossible to save database or to move
newly created row in 'Edit Table' window.

src/sqlitedb.cpp

@@ -285,12 +285,19 @@ bool DBBrowserDB::setSavepoint(const QString& pointname)
 bool DBBrowserDB::releaseSavepoint(const QString& pointname)
 {
     if(!isOpen() || savepointList.contains(pointname) == false)
-        return false;
+        // If there is no such savepoint in the list,
+        // we have already released it, so in this case
+        // the operation should be successfull
+        return true;
 
     QString query = QString("RELEASE %1;").arg(pointname);
     if(!executeSQL(query, false, false))
         return false;
-    savepointList.removeAll(pointname);
+    // SQLite releases all savepoints that were created between
+    // creation of given savepoint and releasing of it,
+    // so we should too
+    int point_index = savepointList.lastIndexOf(pointname);
+    savepointList.erase(savepointList.begin()+point_index, savepointList.end());
     emit dbChanged(getDirty());
 
     return true;
@@ -305,7 +312,11 @@ bool DBBrowserDB::revertToSavepoint(const QString& pointname)
     executeSQL(query, false, false);
     query = QString("RELEASE %1;").arg(pointname);
     executeSQL(query, false, false);
-    savepointList.removeAll(pointname);
+    // SQLite releases all savepoints that were created between
+    // creation of given savepoint and releasing of it,
+    // so we should too
+    int point_index = savepointList.lastIndexOf(pointname);
+    savepointList.erase(savepointList.begin()+point_index, savepointList.end());
     emit dbChanged(getDirty());
 
     return true;