db_query: Query an RSQLite database.

In rcprd: Extraction and Management of Clinical Practice Research Datalink Data

Query an RSQLite database.

Description

Query an RSQLite database stored on the hard disk for observations with specific codes.

Usage

db_query(
  codelist = NULL,
  db_open = NULL,
  db = NULL,
  db_filepath = NULL,
  db_cprd = c("aurum", "gold"),
  tab = c("observation", "drugissue", "clinical", "immunisation", "test", "therapy",
    "hes_primary", "death"),
  table_name = NULL,
  codelist_vector = NULL,
  codelist_df = NULL,
  n = NULL,
  rm_duplicates = FALSE
)

Arguments

codelist	Name of codelist to query the database with.
db_open	An open SQLite database connection created using RSQLite::dbConnect, to be queried.
db	Name of SQLITE database on hard disk, to be queried.
db_filepath	Full filepath to SQLITE database on hard disk, to be queried.
db_cprd	CPRD Aurum ('aurum') or gold ('gold').
tab	CPRD filetype
table_name	Specify name of table in the SQLite database to be queried, if this is different from tab.
codelist_vector	Vector of codes to query the database with.
codelist_df	data.frame used to specify the codelist.
n	number of observations to output
rm_duplicates	TRUE/FALSE whether to remove duplicate values (default is FALSE)

Details

Specifying db requires a specific underlying directory structure. The SQLite database must be stored in "data/sql/" relative to the working directory. If the SQLite database is accessed through db, the connection will be opened and then closed after the query is complete. The same is true if the database is accessed through db_filepath. A connection to the SQLite database can also be opened manually using RSQLite::dbConnect, and then using the object as input to parameter db_open. After wards, the connection must be closed manually using RSQLite::dbDisconnect. If db_open is specified, this will take precedence over db or db_filepath.

Specifying codelist requires a specific underlying directory structure. The codelist on the hard disk must be stored in "codelists/analysis/" relative to the working directory, must be a .csv file, and contain a column "medcodeid", "prodcodeid" or "ICD10" depending on the chosen tab. The codelist can also be read in manually, and supplied as a character vector to codelist_vector. If the codelist is specified through an R data.frame, codelist_df, this must contain a column "medcodeid", "prodcodeid" or "ICD10" depending on the chosen tab. Specifying the codelist this way will retain all the other columns from codelist_df in the queried output.

The argument table_name is only necessary if the name of the table being queried does not match the CPRD filetype specified in tab. This will occur when str_match is used in cprd_extract or add_to_database to create the .sqlite database.

Value

A data.table with observations contained in the specified codelist.

Examples

## Create connection to a temporary database
aurum_extract <- connect_database(file.path(tempdir(), "temp.sqlite"))

## Add observation data from all observation files in specified directory
cprd_extract(db = aurum_extract,
filepath = system.file("aurum_data", package = "rcprd"),
filetype = "observation")

## Query database for a specific medcode
db_query(db_open = aurum_extract,
tab ="observation",
codelist_vector = "187341000000114")

## clean up
RSQLite::dbDisconnect(aurum_extract)
unlink(file.path(tempdir(), "temp.sqlite"))

rcprd documentation built on Sept. 9, 2025, 5:24 p.m.