R - sqldf

R的sqldf包能对dataframe进行sql操作，对于习惯用sql的人来说比较方便。

library(sqldf)

TA <- read.csv('table-A.csv', header = TRUE, sep = ",")
TB <- read.csv('table-B.csv', header = TRUE, sep = ",")

#mergedData <- merge(TA, TB, by = c("BOR_NUM"), all.x = TRUE)

strSql <- "select * from TA
           left join TB
           on TA.BOR_NUM = TB.BOR_NUM"

result <- sqldf(strSql)

详细参见：

https://www.r-bloggers.com/manipulating-data-frames-using-sqldf-a-brief-overview/