library("readxl")
# xls files
my_data <- read_excel("my_file.xls")
# xlsx files
my_data <- read_excel("my_file.xlsx")

#readxl Package
library(readxl)
##Read sheet One by One
read_excel("data.xlsx", sheet = 1, col_names = c("x", "y"), #Default col_names = T col_types = NULL, #Null means R will guess the type itself,	#it can also take "text", "numeric", "date", "blank" skip = 0)
##All
lapply(excel_sheets("data.xlsx"), read_excel, path = "data.xlsx")
##Getting Sheets name
excel_sheets("data.xlsx")
#gdata Package
##Default for xls file type only
##Require extra modules to read xlsx files
library(gdata)
read.xls("data.xls", sheet = 2)
### All sheet argument within this document could be also susbstituted with sheets' name

 
require(RODBC)
conn = odbcConnectExcel("myfile.xlsx") # open a connection to the Excel file
sqlTables(conn)$TABLE_NAME # show all sheets
df = sqlFetch(conn, "Sheet1") # read a sheet
df = sqlQuery(conn, "select * from [Sheet1 $]") # read a sheet (alternative SQL sintax)
close(conn) # close the connection to the file