[Driver] Fix prepared insert statements raising `not enough query arg…

…uments` (#171)

* [Driver] Fix prepared insert statements raising `not enough query arguments`

* use different test table name

driver_test.go

@@ -178,3 +178,66 @@ CREATE TABLE IF NOT EXISTS Singers (
 		}
 	})
 }
+
+func TestPreparedStatements(t *testing.T) {
+	t.Run("prepared select", func(t *testing.T) {
+		db, err := sql.Open("zetasqlite", ":memory:")
+		if err != nil {
+			t.Fatal(err)
+		}
+		if _, err := db.Exec(`
+CREATE TABLE IF NOT EXISTS Singers (
+  SingerId   INT64 NOT NULL,
+  FirstName  STRING(1024),
+  LastName   STRING(1024),
+  SingerInfo BYTES(MAX)
+)`); err != nil {
+			t.Fatal(err)
+		}
+		stmt, err := db.Prepare("SELECT * FROM Singers WHERE SingerId = ?")
+		if err != nil {
+			t.Fatal(err)
+		}
+		rows, err := stmt.Query("123")
+		if err != nil {
+			t.Fatal(err)
+		}
+		if rows.Next() {
+			t.Fatal("found unexpected row; expected no rows")
+		}
+	})
+	t.Run("prepared insert", func(t *testing.T) {
+		db, err := sql.Open("zetasqlite", ":memory:")
+		if err != nil {
+			t.Fatal(err)
+		}
+		if _, err := db.Exec(`CREATE TABLE IF NOT EXISTS Items (ItemId   INT64 NOT NULL)`); err != nil {
+			t.Fatal(err)
+		}
+		if _, err := db.Exec("INSERT `Items` (`ItemId`) VALUES (123)"); err != nil {
+			t.Fatal(err)
+		}
+
+		// Test that executing without args fails
+		_, err = db.Exec("INSERT `Items` (`ItemId`) VALUES (?)")
+		if err == nil {
+			t.Fatal("expected error when inserting without args; got no error")
+		}
+
+		stmt, err := db.Prepare("INSERT `Items` (`ItemId`) VALUES (?)")
+		if err != nil {
+			t.Fatal(err)
+		}
+		if _, err := stmt.Exec(456); err != nil {
+			t.Fatal(err)
+		}
+
+		rows, err := db.Query("SELECT * FROM Items WHERE ItemId = 456")
+		if err != nil {
+			t.Fatal(err)
+		}
+		if !rows.Next() {
+			t.Fatal("expected no rows; expected one row")
+		}
+	})
+}

internal/analyzer.go

@@ -696,6 +696,9 @@ func getParamsFromNode(node ast.Node) []*ast.ParameterNode {
 }
 
 func getArgsFromParams(values []driver.NamedValue, params []*ast.ParameterNode) ([]interface{}, error) {
+	if values == nil {
+		return nil, nil
+	}
 	argNum := len(params)
 	if len(values) < argNum {
 		return nil, fmt.Errorf("not enough query arguments")