🐛 fix(sqlserver): 修复普通查询结果被原生多结果集吃空

- 对只读 SQL 的原生多结果集空返回增加顺序回退兜底
- 避免 optional driver-agent 成功返回空结果时前端只剩日志无结果集
- 补充 SQLServer 读查询空结果回退回归测试

internal/app/methods_db.go

@@ -1000,6 +1000,13 @@ func (a *App) DBQueryMulti(config connection.ConnectionConfig, dbName string, qu
 		return connection.QueryResult{Success: false, Message: err.Error(), QueryID: queryID}
 	}
 
+	// 某些 optional driver-agent 的原生多结果集路径会异常返回“成功但无任何结果集”。
+	// 对只读查询这是不可信信号，回退到逐条执行可以避免普通 SELECT 在结果面板中被吃空。
+	if useNativeMultiResult && allReadOnly && results != nil && len(results) == 0 && len(resultMessages) == 0 {
+		logger.Warnf("DBQueryMulti 原生多结果集返回空结果，将回退逐条执行：%s SQL片段=%q", formatConnSummary(runConfig), sqlSnippet(query))
+		results = nil
+	}
+
 	// 驱动支持多结果集，直接返回
 	if results != nil {
 		return connection.QueryResult{Success: true, Data: results, Messages: resultMessages, QueryID: queryID}

internal/app/methods_db_multi_test.go

@@ -34,6 +34,11 @@ type fakeNativeMultiResultDB struct {
 	multiCalls int
 }
 
+type fakeEmptyNativeMultiResultDB struct {
+	*fakeBatchWriteDB
+	multiCalls int
+}
+
 func (f *fakeNativeMultiResultDB) QueryMulti(query string) ([]connection.ResultSetData, error) {
 	results, _, err := f.QueryMultiWithMessages(query)
 	return results, err
@@ -67,6 +72,28 @@ func (f *fakeNativeMultiResultDB) QueryMultiContextWithMessages(ctx context.Cont
 	}}, append([]string(nil), messages...), nil
 }
 
+func (f *fakeEmptyNativeMultiResultDB) QueryMulti(query string) ([]connection.ResultSetData, error) {
+	results, _, err := f.QueryMultiWithMessages(query)
+	return results, err
+}
+
+func (f *fakeEmptyNativeMultiResultDB) QueryMultiWithMessages(query string) ([]connection.ResultSetData, []string, error) {
+	return f.QueryMultiContextWithMessages(context.Background(), query)
+}
+
+func (f *fakeEmptyNativeMultiResultDB) QueryMultiContext(ctx context.Context, query string) ([]connection.ResultSetData, error) {
+	results, _, err := f.QueryMultiContextWithMessages(ctx, query)
+	return results, err
+}
+
+func (f *fakeEmptyNativeMultiResultDB) QueryMultiContextWithMessages(ctx context.Context, query string) ([]connection.ResultSetData, []string, error) {
+	f.multiCalls++
+	if err := f.queryErr[query]; err != nil {
+		return nil, nil, err
+	}
+	return []connection.ResultSetData{}, nil, nil
+}
+
 func (f *fakeBatchWriteDB) Connect(config connection.ConnectionConfig) error {
 	return nil
 }
@@ -1332,6 +1359,57 @@ func TestDBQueryMultiRunsSQLServerStatisticsBatchNatively(t *testing.T) {
 	}
 }
 
+func TestDBQueryMultiFallsBackWhenNativeReadOnlyBatchReturnsEmptyResults(t *testing.T) {
+	originalNewDatabaseFunc := newDatabaseFunc
+	t.Cleanup(func() {
+		newDatabaseFunc = originalNewDatabaseFunc
+	})
+
+	query := "SELECT 1 AS value"
+	baseDB := &fakeBatchWriteDB{
+		queryMap: map[string][]map[string]interface{}{
+			query: {
+				{"value": 1},
+			},
+		},
+		fieldMap: map[string][]string{
+			query: {"value"},
+		},
+		queryErr: map[string]error{},
+	}
+	fakeDB := &fakeEmptyNativeMultiResultDB{fakeBatchWriteDB: baseDB}
+	newDatabaseFunc = func(dbType string) (db.Database, error) {
+		return fakeDB, nil
+	}
+
+	app := NewAppWithSecretStore(secretstore.NewUnavailableStore("test"))
+	config := connection.ConnectionConfig{Type: "sqlserver", Host: "127.0.0.1", Port: 1433, User: "sa"}
+
+	result := app.DBQueryMulti(config, "master", query, "sqlserver-empty-native-read-fallback-test")
+	if !result.Success {
+		t.Fatalf("expected DBQueryMulti success, got failure: %s", result.Message)
+	}
+	if fakeDB.multiCalls != 1 {
+		t.Fatalf("expected one native multi-result attempt, got %d", fakeDB.multiCalls)
+	}
+	if baseDB.session == nil {
+		t.Fatal("expected empty native result to fall back to pinned session query")
+	}
+	if baseDB.session.queryCalls != 1 {
+		t.Fatalf("expected fallback to query through pinned session once, got %d", baseDB.session.queryCalls)
+	}
+	resultSets, ok := result.Data.([]connection.ResultSetData)
+	if !ok {
+		t.Fatalf("expected []connection.ResultSetData, got %T", result.Data)
+	}
+	if len(resultSets) != 1 {
+		t.Fatalf("expected one fallback result set, got %#v", resultSets)
+	}
+	if got := resultSets[0].Rows[0]["value"]; got != 1 {
+		t.Fatalf("expected fallback SELECT result value=1, got %#v", got)
+	}
+}
+
 func TestDBQueryMultiUsesPinnedSessionForSequentialFallback(t *testing.T) {
 	originalNewDatabaseFunc := newDatabaseFunc
 	t.Cleanup(func() {