# Install R package ctrdata

#### Ralf Herold

#### 2025-07-02

## Install package `ctrdata` on an R system

The R Project website (https://www.r-project.org/) provides installers for the R system. It can be used with software products and graphical user interfaces such as R Studio, or from Visual Studio Code.

General information on the `ctrdata` package is available here: https://rfhb.github.io/ctrdata/.

In R, execute:

    install.packages("ctrdata")

For using the development version of package `ctrdata`, install from GitHub:

    # install package under development
    install.packages(c("remotes"))
    remotes::install_github("rfhb/ctrdata", dependencies = TRUE, build_vignettes = TRUE)

Either of the above should install package `ctrdata` into the user’s library.

## Databases to use

At this time, a PostgreSQL, DuckDB, an SQLite or a MongoDB (local or remote) database can be used with the package `ctrdata`. A full SQLite database is provided in the R package `RSQLite`. Suggested installation instructions for PostgreSQL are here and for a local MongoDB server are here; a remote MongoDB database server is accessible here. See here for a speed comparison of the databases; recommended: DuckDB, PostgreSQL or MongoDB local server.

Purpose | Function call
--- | ---
Create SQLite database connection | `dbc <- nodbi::src_sqlite(dbname = "name_of_my_database", collection = "name_of_my_collection")`
Create DuckDB database connection | `dbc <- nodbi::src_duckdb(dbname = "name_of_my_database", collection = "name_of_my_collection")`
Create MongoDB database connection | `dbc <- nodbi::src_mongo(db = "name_of_my_database", collection = "name_of_my_collection")`
Create PostgreSQL database connection | `dbc <- nodbi::src_postgres(dbname = "name_of_my_database"); dbc[["collection"]] <- "name_of_my_collection"`
Use connection with `ctrdata` functions | `ctrdata::{ctrLoadQueryIntoDb, dbQueryHistory, dbFindIdsUniqueTrials, dbFindFields, dbGetFieldsIntoDf}(con = dbc, ...)`

## Attach and reference package `ctrdata`

After completing the installation, attach the package from the user’s library. This will also check the availability of the additional installation requirements as mentioned above:

    library(ctrdata)

Remember to respect the registers’ terms and conditions (see `ctrOpenSearchPagesInBrowser(copyright = TRUE)`). Please cite this package in any publication as follows: Ralf Herold (2025). ctrdata: Retrieve and Analyze Clinical Trials in Public Registers. R package version 1.23.0. https://cran.r-project.org/package=ctrdata