R语言使用RMySQL连接及读写Mysql数据库

原作者: [db:作者] 来自: [db:来源] 收藏邀请

简单说下安装过程，一般不会有问题，重点是RMySQL的使用方式。

系统环境说明

Redhat系统：Linux 460-42.6.32-431.29.2.el6.x86_64

系统编码：LANG=zh_CN.UTF-8（中文UTF-8格式）

MySQL版本：mysql Ver 14.14 Distrib 5.1.73, forredhat-linux-gnu (x86_64) using readline 5.1

安装mysql

1. 查看是否安装

yum list installed mysql*

2. 查看现有安装包

yumlist mysql*

3. 安装mysql服务器端

yuminstall mysql-devel

yuminstall mysql-server

4. 设置mysql默认字符和引擎

vim/etc/my.cnf

在[mysqld]下添加

default-character-set=utf8

default-storage-engine=INNODB

5. mysql启动和关闭

/etc/init.d/mysqld start

/etc/init.d/mysqld stop

6. 设置开机mysql启动

/sbin/chkconfig - - list

/sbin/chkconfig add mysqld

/sbin/chkconfig mysqld on

安装RMySQL

install.packages(“RMySQL”)

使用RMySQL操作数据库

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library(RMySQL)
help(package=”RMySQL”) #查看RMySQL的说明文档，里面有RMySQL所有可用的方法
#创建数据库连接
con <- dbConnect(MySQL(),host="host",dbname="test_dw",user="user",password="password")
#获取连接信息，查看database下所有表，以及删除testname表
summary(con)
dbGetInfo(con)
dbListTables(con)
dbRemoveTable(con,"test")

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#写数据库表
fruits <-data.frame(id=1:5,name=c("苹果","香蕉","梨子","玉米","西瓜"),price=c(8.8,4.98,7.8,6,2.1),status=c("无","打折","无","售罄","批发"))
dbListTables(con)
dbWriteTable(con,"fruits",fruits)
dbListTables(con)

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#写数据表，覆盖追加
testA <-data.frame(id=1:6,e=c("a","b","c","d","e","f"),c=c("我","的","世","界","变","得"))
testB <-data.frame(id=7:13,e=c("g","h","i","j","k","l","m"),c=c("奇","妙","跟","难","以","言","喻"))
#直接写testA写入test表中
dbWriteTable(con,"test",testA,row.names=F)
dbReadTable(con,"test")
#追加写testB追加在test表后
dbWriteTable(con,"test",testB,append=T,row.names=F)
dbReadTable(con,"test")
#覆盖写testB覆盖test表
dbWriteTable(con,"test",testB,overwrite=T,row.names=F)
dbReadTable(con,"test")

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#用SQL语句批量查询
con <- dbConnect(MySQL(),host="host",dbname="test_dw",user="user",password="password",client.flag= CLIENT_MULTI_STATEMENTS) #client.flag设置这样支持批量查询
dbSendQuery(con,'SET NAMES utf8')
sql <- "SELECT * FROM fruits;SELECT * FROM test"
res1 <- dbSendQuery(con,sql)
dbFetch(res1, n = -1)
if (dbMoreResults(con)) {
res2 <- dbNextResult(con)
dbFetch(res2, n = -1)
}
dbListResults(con)
dbClearResult(res1)
dbClearResult(res2)
dbDisconnect(con)