pythongh-79579: Update sqlite3.Cursor.rowcount for all datamodifying queries

Author: erlend-aasland

Lib/test/test_sqlite3/test_dbapi.py

@@ -887,6 +887,13 @@ def test_rowcount_executemany(self):
         self.cu.executemany("insert into test(name) values (?)", [(1,), (2,), (3,)])
         self.assertEqual(self.cu.rowcount, 3)
 
+    def test_rowcount_prefixed_with_comment(self):
+        # gh-79579: rowcount is updated even if query is prefixed with comments
+        self.cu.execute("/* foo */ insert into test(name) values (?)", ('foo',))
+        self.assertEqual(self.cu.rowcount, 1)
+        self.cu.execute("/* bar */ update test set name='bar' where name='foo'")
+        self.assertEqual(self.cu.rowcount, 2)
+
     def test_total_changes(self):
         self.cu.execute("insert into test(name) values ('foo')")
         self.cu.execute("insert into test(name) values ('foo')")

Misc/NEWS.d/next/Library/2022-06-06-12-58-27.gh-issue-79579.e8rB-M.rst

@@ -0,0 +1,2 @@
+:data:`sqlite3.Cursor.rowcount` is now correctly updated for all datamodifying
+SQL queries.  Patch by Erlend E. Aasland.

Modules/_sqlite/cursor.c

@@ -944,7 +944,7 @@ _pysqlite_query_execute(pysqlite_Cursor* self, int multiple, PyObject* operation
             }
         }
 
-        if (self->statement->is_dml) {
+        if (!sqlite3_stmt_readonly(self->statement->st)) {
             self->rowcount += (long)sqlite3_changes(self->connection->db);
         } else {
             self->rowcount= -1L;