update an SQL table via R sqlSave - sql

Question

I have a data frame in R having 3 columns, using sqlSave I can easily create a table in an SQL database:
channel <- odbcConnect("JWPMICOMP")
sqlSave(channel, dbdata, tablename = "ManagerNav", rownames = FALSE, append = TRUE, varTypes = c(DateNav = "datetime"))
odbcClose(channel)
This data frame contains information about Managers (Name, Nav and Date) which are updatede every day with new values for the current date and maybe old values could be updated too in case of errors.
How can I accomplish this task in R?
I treid to use sqlUpdate but it returns me the following error:
> sqlUpdate(channel, dbdata, tablename = "ManagerNav")
Error in sqlUpdate(channel, dbdata, tablename = "ManagerNav") :
cannot update ‘ManagerNav’ without unique column

Answer 1

When you create a table "the white shark-way" (see documentation), it does not get a primary index, but is just plain columns, and often of the wrong type. Usually, I use your approach to get the columns names right, but after that you should go into your database and assign a primary index, correct column widths and types.
After that, sqlUpdate() might work; I say might, because I have given up using sqlUpdate(), there are too many caveats, and use sqlQuery(..., paste("Update....))) for the real work.

Answer 2

What I would do for this is the following
Solution 1
sqlUpdate(channel, dbdata,tablename="ManagerNav", index=c("ManagerNav"))
Solution 2
Lcolumns <- list(dbdata[0,])
sqlUpdate(channel, dbdata,tablename="ManagerNav", index=c(Lcolumns))
Index is used to specify what columns R is going to update.
Hope this helps!

Answer 3

If none of the other solutions work and your data is not that big, I'd suggest using sqlQuery() and loop through your dataframe.
one_row_of_your_df <- function(i) {
sql_query <-
paste0("INSERT INTO your_table_name (column_name1, column_name2, column_name3) VALUES",
"(",
"'",your_dataframe[i,1],",",
"'",your_dataframe[i,2],"'",",",
"'",your_dataframe[i,3],"'",",",
")"
)
return(sql_query)
}
This function is Exasol specific, it is pretty similar to MySQL, but not identical, so small changes could be necessary.
Then use a simple for loop like this one:
for(i in 1:nrow(your_dataframe))
{
sqlQuery(your_connection, one_row_of_your_df(i))
}