query_database {DIZutils}

query_database helper function

Description

Internal function to query the database. The function sends a sql statement to the database and returns a data.table.

Usage

query_database(
  db_con,
  sql_statement,
  no_result = FALSE,
  close_connection = FALSE
)

Arguments

db_con

A DBI database connection.

sql_statement

A character string containing a valid SQL statement. Caution: Everything after the first ';' will be cut off.

no_result

(boolean, default: FALSE) Is the sql meant to return nothing? E.g. if you just insert or update a table. Then supply 'TRUE' here. If you supply 'FALSE' here, the function expects to receive a result table and tries to convert it to a data.table.

close_connection

(boolean, default = FALSE). If TRUE, the connection will be closed after the query was sent and the result received.

Value

Returns the result of the db-query. If 'no_result' is 'TRUE', the return value will be 'TRUE' if the query was successfully sent. Otherwise (if 'no_result' is 'FALSE' which is the default), the result will be the result of the sql query as data.table.

Examples

## Not run: 
db_con <- DIZutils::db_connection(
  db_name = "i2b2",
  db_type = "postgres"
)

query_database(
  db_con = db_con,
  sql_statement = "SELECT * FROM table_name;"
)

query_database(
  db_con = db_con,
  sql_statement = "INSERT INTO table_name DEFAULT VALUES;",
  no_result = TRUE
)


## End(Not run)