我有一个R的工作知识,但是我并没有太多地使用数据库.我的问题似乎非常类似于这个问题：
update table in postgresql database through r
update table in postgresql database through r
但是我无法使该代码工作,并且doMC软件包不适用于最新版本的R
我可以连接到地理数据库,读入数据并进行操作.我也可以将R对象作为整个表写入地理数据库.我有麻烦,附加一个现有的地理数据库表与一个R对象.不幸的是,它是一个安全的数据库,所以我无法给出我的连接信息.
– “穿着”,“工作日”和“天”是地理数据库中预先存在的表中的空白列
– “participant_id”,“date_id”和“gps_time”是我想要合并的预先存在的表中的填充列.
-ucsd是模式名,sage_choi是现有的表名
choifnl <- structure(list(wearing = structure(c(1L,1L,1L),.Label = c("nw","w"),class = "factor"),weekday = c("Saturday","Saturday","Saturday"),days = c(1,1,1),participant_id = c("0adf37c4-f950-40ad-9370-6bee2f93e935","0adf37c4-f950-40ad-9370-6bee2f93e935","0adf37c4-f950-40ad-9370-6bee2f93e935"),date = c("20130202","20130202","20130202"),time = structure(1:6,.Label = 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= "factor")),.Names = c("wearing","weekday","days","participant_id","date","time"),row.names = c(NA,6L),class = "data.frame")
update <- function(i) {
drv <- dbDriver("Postgresql")
con <- dbConnect(drv,dbname = "",host = "",port <-,user = "",password = "") ##connect w/username and password
txt <- paste("UPDATE ucsd.sage_choi SET wearing=",choifnl$wearing[i],",weekday=",choifnl$weekday[i],days=",choifnl$days[i],where participant_id=",choifnl$participant_id[i],AND date_id=",choifnl$date[i],"AND gps_time=",choifnl$time[i])
dbGetQuery(con,txt)
dbDisconnect(con)
}
library("foreach")
registerDoMC()
foreach(i = 1:length(choifnl$wearing),.inorder=FALSE,.packages="RPostgresql")%dopar%{
update(i)
}
####编辑
这是最终的解决方案(连接信息略),效果很好.我有一些编码问题,还包括正确的引号(单).
update <- function(con,i) {
txt <- paste("UPDATE ucsd.sage_final_choi SET wearing=",paste("'","'",sep=""),"WHERE participant_id=","AND date_id=",choifnl$time[i],";")
dbSendQuery(con,txt) # edit 2
}
drv <- dbDriver("Postgresql")
con <- dbConnect(drv,port <- 5432,password = "",options="-c search_path= schemaName") ##connect w/username and password
foreach(i = 1:length(choifnl$wearing),.packages="RPostgresql")%do%{
update(con,i) # passing in the open connection as an argument
}
解决方法
我假设在这里你正在使用CRAN库RPostgresql,而你的问题是,
“如何使用R更新现有的postgresql记录？”
如果我正确地解释你的问题,我有个好消息,我会对你现有的代码做一些小的修改,让它在下面工作.现在的好消息是：
>错误在你的sql和
>你不需要doMC(也不是foreach,对于这个问题).
>你已经连接到你的数据库 – 这通常是更繁重的部分！
如果您真的需要并行性,您可以看到使用doSNOW初始化多个工作人员的基本格式.无论哪种方式,调试单线程应用程序要容易得多,因此您应该直接将循环更改为单线程循环,方法是将foreach语句末尾的％dopar％参数更改为％do％,然后注册在你得到sql的工作之后你的并行后端.
foreach(i = 1:length(choifnl$wearing),.packages="RPostgresql") %do% { update(i) }
那么你可能会看到你的sql有一个语法错误,特别是在那个“where”和你的第一个“和”错误地跟随逗号.我通常将大型语句分解成更可读的形式,如下所示,因此更容易发现形式的不一致.我删除了以下这段代码中的无意的逗号：
### sql error resolved update <- function(i) { drv <- dbDriver("Postgresql") con <- dbConnect(drv,password = "") ##connect w/username and password txt <- paste("UPDATE ucsd.sage_choi SET wearing=","where participant_id=",choifnl$time[i]) dbGetQuery(con,txt) dbDisconnect(con) }
从性能的角度来看,如果您在for循环之外初始化连接,那么您将不再需要为每条记录重新建立连接所需的时间和成本.
### sql error resolved,connection made outside loop update <- function(con,i) { txt <- paste("UPDATE ucsd.sage_choi SET wearing=",choifnl$time[i]) dbSendQuery(con,txt) # edit 2 } drv <- dbDriver("Postgresql") con <- dbConnect(drv,password = "") ##connect w/username and password foreach(i = 1:length(choifnl$wearing),.packages="RPostgresql")%dopar%{ update(con,i) # passing in the open connection as an argument } dbDisconnect(con)
