Merge pull request #9394 from Tishj/python_execute_multi_statements

[Python] Throw explicit error for misuse of `execute`

tools/pythonpkg/src/pyconnection.cpp

@@ -47,6 +47,7 @@
 #include "duckdb_python/pybind11/conversions/exception_handling_enum.hpp"
 #include "duckdb/parser/parsed_data/drop_info.hpp"
 #include "duckdb/catalog/catalog_entry/scalar_function_catalog_entry.hpp"
+#include "duckdb/main/pending_query_result.hpp"
 
 #include <random>
 
@@ -448,7 +449,11 @@ unique_ptr<QueryResult> DuckDBPyConnection::ExecuteInternal(const string &query,
 		// if there are multiple statements, we directly execute the statements besides the last one
 		// we only return the result of the last statement to the user, unless one of the previous statements fails
 		for (idx_t i = 0; i + 1 < statements.size(); i++) {
-			// TODO: this doesn't take in any prepared parameters?
+			if (statements[i]->n_param != 0) {
+				throw NotImplementedException(
+				    "Prepared parameters are only supported for the last statement, please split your query up into "
+				    "separate 'execute' calls if you want to use prepared parameters");
+			}
 			auto pending_query = connection->PendingQuery(std::move(statements[i]), false);
 			auto res = CompletePendingQuery(*pending_query);
 

tools/pythonpkg/tests/fast/api/test_duckdb_execute.py

@@ -0,0 +1,38 @@
+import duckdb
+import pytest
+
+
+class TestDuckDBExecute(object):
+    def test_execute_basic(self, duckdb_cursor):
+        duckdb_cursor.execute('create table t as select 5')
+        res = duckdb_cursor.table('t').fetchall()
+        assert res == [(5,)]
+
+    def test_execute_many_basic(self, duckdb_cursor):
+        duckdb_cursor.execute("create table t(x int);")
+
+        # This works because prepared parameter is only present in the last statement
+        duckdb_cursor.execute(
+            """
+			delete from t where x=5;
+			insert into t(x) values($1);
+		""",
+            (99,),
+        )
+        res = duckdb_cursor.table('t').fetchall()
+        assert res == [(99,)]
+
+    def test_execute_many_error(self, duckdb_cursor):
+        duckdb_cursor.execute("create table t(x int);")
+
+        # Prepared parameter used in a statement that is not the last
+        with pytest.raises(
+            duckdb.NotImplementedException, match='Prepared parameters are only supported for the last statement'
+        ):
+            duckdb_cursor.execute(
+                """
+				delete from t where x=$1;
+				insert into t(x) values($1);
+			""",
+                (99,),
+            )