`knitr`可以抑制执行或在SQL块中输出吗? [英] Can `knitr` suppress execution or output in an sql chunk?

问题描述

下面的文档运行sql并显示结果.我不希望通过不运行块或隐藏输出来显示任何输出.

The document below runs the sql and shows the results. I don't want any output to show up, either by not running the chunk, or by hiding the output.

有没有办法做到这一点?

Is there a way to do this?

---
output: html_document
---

## Hide SQL Output

First, set up a temporary database:

```{r}
library(RSQLite)
conn <- dbConnect(SQLite(), tempfile())
df <- data.frame(value = runif(1))
dbWriteTable(conn, "TestTable", df)
```

Now show a query, but try not to run it, and try
to hide the output.  Neither works:  it runs, and 
displays the table.

```{sql connection = conn,results="hide",eval=FALSE}
SELECT * FROM TestTable;
```

我得到以下输出:

推荐答案

我找到了一种解决方法.如果我使用mysql引擎而不是sql引擎，那么至少eval = FALSE可以工作:

I found a workaround. If I use the mysql engine instead of the sql engine, then at least eval = FALSE works:

```{mysql eval=FALSE}
SELECT * FROM TestTable;
```

将以突出显示语法的方式显示代码，但不执行任何操作.

will display the code with syntax highlighting but not execute anything.

我不知道是否还支持results="hide"，因为我没有安装mysql.

I don't know if results="hide" is also supported, because I don't have mysql installed.

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