Question

我想多次重复使用子查询。

首先计算

---
title: "Untitled"
author: "John Doe"
date: "November 18, 2016"
documentclass: article
output:
  bookdown::pdf_document2:
    toc: yes
    fig_caption: yes
    number_sections: yes
linkcolor: blue
---

# Chapter One

```{r a, fig.cap="rabble rabble"}
plot(cars) # a scatterplot
```

```{r b, fig.cap="rabble rabble"}
plot(cars) # a scatterplot
```

# Chapter Two

# (APPENDIX) Appendix {-}
# Appendix A

```{r c, fig.cap="rabble rabble"}
plot(cars) # a scatterplot
```

# Appendix B

```{r d, fig.cap="rabble rabble"}
plot(cars) # a scatterplot
```

子查询，如

 devices = db.session.query(subquery).count()

然后用限制对结果进行分页。我想重用我的过滤器

 (Device, User).\
                    filter(Device.e=='E').\
                 filter(Device.id==User.id

并且不要重复，因为我使用了这么多的过滤器和过滤器可能会改变

Answer 1

答案实际上非常简单。

def getquery(self):
  return db.session.query(subquery)

为计数

count = self.getquery().count()

限制

devices = self.getquery().limit(xxxx)

Sqlalchemy重用子查询

1 个答案: