Writing and Updating DB2 tables with r

问题

I can't figure out how to update an existing DB2 database in R or update a single value in it.

I can't find much information on this topic online other than very general information, but no specific examples.

        library(RJDBC)

        teachersalaries=data.frame(name=c("bob"), earnings=c(100))




        dbSendUpdate(conn, "UPDATE test1 salary",teachersalaries[1,2])

AND

       teachersalaries=data.frame(name=c("bob",'sally'), earnings=c(100,200))




        dbSendUpdate(conn, "INSERT INTO test1 salary", teachersalaries[which(teachersalaries$earnings>200,] )

回答1:

Have you tried passing a regular SQL statement like you would in other languages?

dbSendUpdate(conn, "UPDATE test1 set salary=? where id=?", teachersalary, teacherid)

dbSendUpdate(conn,"INSERT INTO test1 VALUES (?,?)",teacherid,teachersalary)

Basically you specify the regular SQL DML statement using parameter markers (those question marks) and provide a list of values as comma-separated parameters.

回答2:

Try this, it worked for me well.

dbSendUpdate(conn,"INSERT INTO test1 VALUES (?,?)",teacherid,teachersalary)

You just need to pass a regular SQL piece in the same way you do in any programing langs. Try it out.

回答3:

To update multiple rows at the same time, I have built the following function.

I have tested it with batches of up to 10,000 rows and it works perfectly.

# Libraries
library(RJDBC)
library(dplyr)    

# Function upload data into database
db_write_table <- function(conn,table,df){
  # Format data to write
  batch <- apply(df,1,FUN = function(x) paste0("'",trimws(x),"'", collapse = ",")) %>%
  paste0("(",.,")",collapse = ",\n")

  #Build query
  query <- paste("INSERT INTO", table ,"VALUES", batch)

  # Send update
  dbSendUpdate(conn, query)
}

# Push data
db_write_table(conn,"schema.mytable",mydataframe)

Thanks to the other authors.

来源：https://stackoverflow.com/questions/35324001/writing-and-updating-db2-tables-with-r

标签

database

db2

rjdbc