RH2:连接到R中的H2数据库 [英] RH2: Connect to H2 Database in R

问题描述

我尝试将RH2连接到H2(1.4.181)数据库.我尝试了不同的操作，例如重新安装R，并在Ubuntu上修复了rJava的潜在问题.但是以下错误不会消失:

I tried to connect with RH2 to a H2 (1.4.181) Database. I've tried different things, like reinstalling R, and fixing potential problems with rJava on Ubuntu. However following error does not disappear:

> library("RH2")
Loading required package: chron
Loading required package: RJDBC
Loading required package: DBI
Loading required package: rJava
> con <- dbConnect(H2(driverClass="org.h2.Driver", jars =    "~/h2-1.4.181.jar"), "jdbc:h2:~/test", "sa", "")
Error in is(object, Cl): error in evaluating the argument 'drv' in selecting a method for function   'dbConnect': Error in .jfindClass(as.character(driverClass)[1]) : class not found

有人知道如何解决这个问题，还是我在语法上犯了一个错误?

Does anyone know how to solve this or did I make a mistake in the syntax?

推荐答案

我认为jars参数已损坏.我的猜测是它不是在前面.

I think the jars argument is broken. My guess is that it isn't pre-pending.

我通过在更新的软件包库中替换了旧的H2 jar包(在Mac OS X上)对其进行了修复.具体来说:

I fixed it (on Mac OS X) by replacing the old H2 jar in my package library with an updated one. Specifically:

 box:java nmvanhoudnos$ pwd
 /Users/nmvanhoudnos/Library/R/3.2/library/RH2/java
 box:java nmvanhoudnos$ ls
 h2-1.3.175.jar
 box:java nmvanhoudnos$ mv h2-1.3.175.jar h2-1.3.175.old
 box:java nmvanhoudnos$ cp ~/workspace/defectprediction/h2*.jar .
 box:java nmvanhoudnos$ ls
 h2-1.3.175.old h2-1.4.184.jar

您将需要在其中针对操作系统，文件系统和更新H2 jar的位置进行适当的更改.

Where you will need to make the appropriate changes for your OS, filesystem, and location of the update H2 jar.

一旦有了新的jar文件，就可以测试它在R中的工作方式，如下所示:

Once you have the new jar file in place, you can test that it works in R as follows:

> library(RH2)
> con <- dbConnect(H2())
> s <- "select VALUE from INFORMATION_SCHEMA.SETTINGS where NAME = 'info.VERSION'"
> dbGetQuery(con, s)
                 VALUE
1 1.4.184 (2014-12-19)

符合预期.

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