prepare_sql {sqlhelper}

prepare queries and assemble meta data prior to execution

Description

Except for sql, parameters are default values to be used when none are supplied in sql (i.e. when sql is a tibble returned by read_sql()).

Usage

prepare_sql(
  sql,
  quotesql = "yes",
  values = parent.frame(),
  execmethod = "get",
  geometry = NA,
  default.conn = default_conn()
)

Arguments

sql

An optionally-named list or character vector containing sql commands, or a tibble returned by read_sql()

quotesql

"yes" or "no" - should interpolated characters be quoted by default? Anything that isn't "no" is treated as "yes".

values

An environment containing variables to interpolate into the SQL. Pass any object that is not an environment (commonly-used options include "no", NA, FALSE or NULL) if interpolation is to be skipped, or another environment containing values to interpolate to avoid using .GlobalEnv.

execmethod

One of "get", "execute", "sendq", "sends" or "spatial" - which method should be used to execute the query? "get" means DBI::dbGetQuery(); "execute" means DBI::dbExecute(); "sendq" means DBI::dbSendQuery; "sends" means DBI::dbSendStatement(); "spatial" means sf::st_read().

geometry

If execmethod is "spatial", which column contains the geometry? Ignored if execmethod is not "spatial".

default.conn

Either the name of a sqlhelper connection, or a database connection returned by DBI::dbConnect() or pool::pool(), or NA. This connection is only used by glue::glue_sql() to quote SQL interpolations; prepare_sql() does not execute any SQL code.

Details

The default.conn parameter may be used to supply a connection object that is not a configured sqlhelper connection which can then be used to interpolate quoted strings.

Value

A tibble containing 1 row per query with the following fields:

qname

character. A name for this query

quotesql

"yes" or "no". Should parameterized character values be quoted for this query?

interpolate

"yes" or "no". Should this query be parameterized with values from R?

execmethod

The method to execute this query. One of "get" (DBI::dbGetQuery()), "execute" (DBI::dbExecute()), "sendq" (DBI::dbSendQuery()), "sends" (DBI::dbSendStatement()) or "spatial" (sf::st_read())

geometry

character. If execmethod is "spatial", which is the geometry column?

conn_name

character. The name of the database connection to use for this query. Must be the name of a configured sqlhelper connection.

sql

The sql query as entered

filename

The value of file_name

prepared_sql

The sql query to be executed, i.e. with interpolations and quoting in place

Examples

library(sqlhelper)
connect(
    system.file("examples/sqlhelper_db_conf.yml",
                package="sqlhelper"),
    exclusive = TRUE
)

n <- 5
foo <- 'bar'
prepped <- prepare_sql(c("select {`foo`}", "select {n}"))
prepped
prepped$prepared_sql