Regarding ROracle library in R...
Every time I create a table using dbWriteTable, when I select it inside an Oracle Client I have to put quotes around the table name like:
select * from "table_name"
That is super annoying, how to get rid of the quotes? What do I need to tweak so that this works:
select * from table_name
I tried a bunch of things but this worked:
dbWriteTable(conn, "MYTABLE", df, rownames = F, append = T, overwrite = F)
What is nice about this is that in case MYTABLE does not exist, it creates it for you. Now you can do:
select * from mytable;
//Edit:
If you create a table with this, it is important to ensure that your column names are upper case.
colnames(df) <- toupper(colnames(df)) # in R
dbWriteTable(conn, "MYTABLE", df, rownames = F, append = T, overwrite = F)
-- in SQL
select col1 from mytable; -- works
If you write the column names as lowercase, you will need to quote the columns in your select statement:
select "col1" from mytable; -- works
select col1 from mytable; -- doesn't work
Related
I use DBI package to write values to my database tables. Database is PostgreSQL.
My data looks like this. Some of my values have 0 digits, some have 1:
I get this data from reading csv using xlsx library.
I use this code to write data to my table:
DBI::dbWriteTable(conn = con,
name = Id(schema = "schema", table = 'table'),
value = df,
append=T,)
But in database I end up with this:
Column types of min_limit and max_limit in database are numeric.
I tried to use:
DBI::dbWriteTable(conn = con,
name = Id(schema = "schema", table = 'table'),
value = format(df, digits = 2),
append=T,)
But this gives me error:
> Error while preparing parameters ERROR: column "row_names" of relation "table" does not exist
What do I need to do to write rounded to 2 digits values to database table?
I'm just starting my journey with r, so I'm a complete newbie and I can't find anything that will help me solve this.
I have a csv table (random integers in each column) with 9 columns. I read 8 and I want to append them to a sql table with 8 fields (Col1 ... 8, all int's). After uploading the csv into rStudio, it looks right and only has 8 columns:
The code I'm using is:
# Libraries
library(DBI)
library(odbc)
library(tidyverse )
# CSV Files
df = head(
read_delim(
"C:/Data/test.txt",
" ",
trim_ws = TRUE,
skip = 1,
skip_empty_rows = TRUE,
col_types = cols('X7'=col_skip())
)
, -1
)
# Add Column Headers
col_headings <- c('Col1', 'Col2', 'Col3', 'Col4', 'Col5', 'Col6', 'Col7', 'Col8')
names(df) <- col_headings
# Connect to SQL Server
con <- dbConnect(odbc(), "SQL", timeout = 10)
# Append data
dbAppendTable(conn = con,
schema = "tmp",
name = "test",
value = df,
row.names = NULL)
I'm getting this error message:
> Error in result_describe_parameters(rs#ptr, fieldDetails) :
> Query requires '8' params; '18' supplied.
I ran into this issue also. I agree with Hayward Oblad, the dbAppendTable function appears to be finding another table of the same name throwing the error. Our solution was to specify the name parameter as an Id() (from DBI::Id())
So taking your example above:
# Append data
dbAppendTable(conn = con,
name = Id(schema = "tmp", table = "test"),
value = df,
row.names = NULL)
Ran into this issue...
Error in result_describe_parameters(rs#ptr, fieldDetails) : Query
requires '6' params; '18' supplied.
when saving to a snowflake database and couldn't find any good information on the error.
Turns out that there was a test schema where the tables within the schema had exactly the same names as in the prod schema. DBI::dbAppendTable() doesn't differentiate the schemas, so until those tables in the text schema got renamed to unique table names, the params error persisted.
Hope this saves someone the 10 hours I spent trying to figure out why DBI was throwing the error.
See he for more on this.
ODBC/DBI in R will not write to a table with a non-default schema in R
add the name = Id(schema = "my_schema", table = "table_name") to DBI::dbAppendTable()
or in my case it was the DBI::dbWriteTable().
Not sure why the function is not using the schema from my connection object though.. seems redundant.
I'm writing to sqlite db from R using the following command:
dbWriteTable(con, 'topics',as.data.frame(topics), row.names = NA, overwrite = FALSE, append = TRUE, field.types = NULL)
I get the following table in sqlite:
How can I rename the row_names attribute?
The df [as.data.frame(topics)] snippet is:
This is what the row.names argument to dbWriteTable is for: Set it to a character value to rename the column, set it to NULL to avoid writing it altogether. Explore the guessRowName() function in the DBI package for other options.
I am using R to try and connect to a teradata database and am running into difficulties
The steps in the process are below
1) Create Connection
2) Create a VOLATILE TABLE
3) Load information from a data frame into the Volatile table
Here is where it fails, giving me an error message
Error in sqlSave(conn, mydata, tablename = "TEMP", rownames = FALSE, :
first argument is not an open RODBC channel
The code is below
# Import Data From Text File and remove duplicates
mydata = read.table("Keys.txt")
mydata.unique = unique(mydata)
strSQL.TempTable = "CREATE VOLATILE TABLE TEMP………[Table Details]"
"UNIQUE PRIMARY INDEX(index)"
"ON COMMIT PRESERVE ROWS;"
# Connect To Database
conn <- tdConnect('Teradata')
# Execute Temp Table
tdQuery(strSQL.TempTable)
sqlSave(conn, mydata, tablename = "TEMP ",rownames = FALSE, append = TRUE)
Can anyone help, Is it closing off the connection before I can upload the information into the Table?
My Mistake, I have been confusing libraries
Basically the lines
# Connect To Database
conn <- tdConnect('Teradata')
# Execute Temp Table
tdQuery(strSQL.TempTable)
sqlSave(conn, mydata, tablename = "TEMP ",rownames = FALSE, append = TRUE)
can all be replaced by this
# Connect To Database
channel <- odbcConnect('Teradata')
# Execute Temp Table
sqlQuery(channel, paste(strSQL.TempTable))
sqlSave(channel, mydata, table = "TEMP",rownames = FALSE, append = TRUE)
Now I'm being told, i don't have access to do this but this is another question for another forum
Thanks
I have an SQLite database connection to a database file. I want to extract some data from one of the tables, do some processing in R and then create a temporary table on the same connection from the processed data. It needs to be a temp table because users may not have write access to the database, but I want to be able to query this new data alongside the data already in the database.
so, for example:
require(sqldf)
db <- dbConnect(SQLite(), "tempdb")
dbWriteTable(db, "iris", iris)
# do some processing in R:
d <- dbGetQuery(db, "SELECT Petal_Length, Petal_Width FROM iris;")
names(d) <- c("length_2", "width_2")
d <- exp(d)
and then I want to make a temporary table in the connection db from d
I know I could do:
dbWriteTable(conn=db, name= "iris_proc", value = d)
but I need it in a temp table and there doesn't seem to be an option for this in dbWriteTable.
One workaround I thought of was to add a temp table and then add columns and update them:
dbGetQuery(db, "CREATE TEMP TABLE iris_proc AS SELECT Species FROM iris;")
dbGetQuery(db, "ALTER TABLE iris_proc ADD COLUMN length_2;")
But then I can't get the data from d into the columns:
dbGetQuery(db, paste("UPDATE iris2 SET length_2 =", paste(d$length_2, collapse = ", "), ";"))
Error in sqliteExecStatement(con, statement, bind.data) :
RS-DBI driver: (error in statement: near "4.05519996684467": syntax error)
I imagine that, even if I get this to work, it will be horribly inefficient.
I thought there might have been some way to do this with read.csv.sql but this does not seem to work with open connection objects.
Use an in-memory database for the temporary table:
library(RSQLite)
db <- dbConnect(SQLite(), "tempdb")
dbWriteTable(db, "iris", iris)
d <- dbGetQuery(db, "SELECT Petal_Length, Petal_Width FROM iris")
d <- exp(d)
dbGetQuery(db, "attach ':memory:' as mem")
dbWriteTable(db, "mem.d", d, row.names = FALSE) # d now in mem database
dbGetQuery(db, "select * from iris limit 3")
dbGetQuery(db, "select * from mem.d limit 3")
dbGetQuery(db, "select * from sqlite_master")
dbGetQuery(db, "select * from mem.sqlite_master")