How to import CSV into sqlite using RSqlite?

问题:

As question, I found that I can use .import in sqlite shell, but seems it is not working in R environment, any suggestions?

回答1:

You can use read.csv.sql in the sqldf package. It is only one line of code to do the read. Assuming you want to create a new database, testingdb, and then read a file into it try this:

# create a test file
write.table(iris, "iris.csv", sep = ",", quote = FALSE, row.names = FALSE)

# create an empty database.
# can skip this step if database already exists.
sqldf("attach testingdb as new")
# or: cat(file = "testingdb")

# read into table called iris in the testingdb sqlite database
library(sqldf)
read.csv.sql("iris.csv", sql = "create table main.iris as select * from file", 
  dbname = "testingdb")

# look at first three lines
sqldf("select * from main.iris limit 3", dbname = "testingdb")

The above uses sqldf which uses RSQLite. You can also use RSQLite directly. See ?dbWriteTable in RSQLite. Note that there can be problems with line endings if you do it directly with dbWriteTable that sqldf will automatically handle (usually).

If your intention was to read the file into R immediately after reading it into the database and you don't really need the database after that then see:

http://code.google.com/p/sqldf/#Example_13._read.csv.sql_and_read.csv2.sql

回答2:

I tend to do that with the sqldf package: Quickly reading very large tables as dataframes in R

Keep in mind that in the above example I read the csv into a temp sqlite db. You'll obviously need to change that bit.