About
ore snippet
Prerequisite
Snippets
Load Data Frame to table
Load Data Frame to table
ore.drop(table = "IRIS_TABLE")
# If IRIS_TABLE doesn't exist, you do not get a message.
# create a database table with the data contained in iris
ore.create(iris, table = "IRIS_TABLE")
List the table
ore.ls()
Copy a table
Create IRIS_TABLE_N that does not contain SPECIES, the nonnumeric column:
IRIS_TABLE_N=IRIS_TABLE[,c("SEPAL_LENGTH", "SEPAL_WIDTH", "PETAL_LENGTH", "PETAL_WIDTH")]
NULL
The sample null.R is the only sample that does not use iris as data. null.R compares the handling of NULLs in SQL with the handling of NAs in R.
R code
- Return all observations where ozone < 30
nrow(airquality[airquality$Ozone < 30,])
92
- results when NAs are explicitly excluded
nrow(airquality[airquality$Ozone < 30 & !is.na(airquality$Ozone),])
55
ORE Code
- The default behavior for SQL tables is to exclude NULLS in output
ore.drop(table = "AIRQUALITY")
ore.create(airquality, table = "AIRQUALITY")
nrow(AIRQUALITY[AIRQUALITY$OZONE < 30,])
55
- To handle NULLs the same way that R handles NA, request the behavior explicitly
options(ore.na.extract = TRUE)
nrow(AIRQUALITY[AIRQUALITY$OZONE < 30,])
92