R glue glue_sql 使用 SQL 轉義插入字符串

glue_sql(..., .con, .envir = parent.frame(), .na = DBI::SQL("NULL"))

glue_data_sql(.x, ..., .con, .envir = parent.frame(), .na = DBI::SQL("NULL"))

glue_sql_collapse() 折疊 DBI::SQL() 對象。

con <- DBI::dbConnect(RSQLite::SQLite(), ":memory:")
iris2 <- iris
colnames(iris2) <- gsub("[.]", "_", tolower(colnames(iris)))
DBI::dbWriteTable(con, "iris", iris2)
var <- "sepal_width"
tbl <- "iris"
num <- 2
val <- "setosa"
glue_sql("
  SELECT {`var`}
  FROM {`tbl`}
  WHERE {`tbl`}.sepal_length > {num}
    AND {`tbl`}.species = {val}
  ", .con = con)
#> <SQL> SELECT `sepal_width`
#> FROM `iris`
#> WHERE `iris`.sepal_length > 2
#>   AND `iris`.species = 'setosa'

# If sepal_length is store on the database as a character explicitly convert
# the data to character to quote appropriately.
glue_sql("
  SELECT {`var`}
  FROM {`tbl`}
  WHERE {`tbl`}.sepal_length > {as.character(num)}
    AND {`tbl`}.species = {val}
  ", .con = con)
#> <SQL> SELECT `sepal_width`
#> FROM `iris`
#> WHERE `iris`.sepal_length > '2'
#>   AND `iris`.species = 'setosa'


# `glue_sql()` can be used in conjuction with parameterized queries using
# `DBI::dbBind()` to provide protection for SQL Injection attacks
 sql <- glue_sql("
    SELECT {`var`}
    FROM {`tbl`}
    WHERE {`tbl`}.sepal_length > ?
  ", .con = con)
query <- DBI::dbSendQuery(con, sql)
DBI::dbBind(query, list(num))
DBI::dbFetch(query, n = 4)
#>   sepal_width
#> 1         3.5
#> 2         3.0
#> 3         3.2
#> 4         3.1
DBI::dbClearResult(query)

# `glue_sql()` can be used to build up more complex queries with
# interchangeable sub queries. It returns `DBI::SQL()` objects which are
# properly protected from quoting.
sub_query <- glue_sql("
  SELECT *
  FROM {`tbl`}
  ", .con = con)

glue_sql("
  SELECT s.{`var`}
  FROM ({sub_query}) AS s
  ", .con = con)
#> <SQL> SELECT s.`sepal_width`
#> FROM (SELECT *
#> FROM `iris`) AS s

# If you want to input multiple values for use in SQL IN statements put `*`
# at the end of the value and the values will be collapsed and quoted appropriately.
glue_sql("SELECT * FROM {`tbl`} WHERE sepal_length IN ({vals*})",
  vals = 1, .con = con)
#> <SQL> SELECT * FROM `iris` WHERE sepal_length IN (1)

glue_sql("SELECT * FROM {`tbl`} WHERE sepal_length IN ({vals*})",
  vals = 1:5, .con = con)
#> <SQL> SELECT * FROM `iris` WHERE sepal_length IN (1, 2, 3, 4, 5)

glue_sql("SELECT * FROM {`tbl`} WHERE species IN ({vals*})",
  vals = "setosa", .con = con)
#> <SQL> SELECT * FROM `iris` WHERE species IN ('setosa')

glue_sql("SELECT * FROM {`tbl`} WHERE species IN ({vals*})",
  vals = c("setosa", "versicolor"), .con = con)
#> <SQL> SELECT * FROM `iris` WHERE species IN ('setosa', 'versicolor')

# If you need to reference variables from multiple tables use `DBI::Id()`.
# Here we create a new table of nicknames, join the two tables together and
# select columns from both tables. Using `DBI::Id()` and the special
# `glue_sql()` syntax ensures all the table and column identifiers are quoted
# appropriately.

iris_db <- "iris"
nicknames_db <- "nicknames"

nicknames <- data.frame(
  species = c("setosa", "versicolor", "virginica"),
  nickname = c("Beachhead Iris", "Harlequin Blueflag", "Virginia Iris"),
  stringsAsFactors = FALSE
)

DBI::dbWriteTable(con, nicknames_db, nicknames)

cols <- list(
  DBI::Id(table = iris_db, column = "sepal_length"),
  DBI::Id(table = iris_db, column = "sepal_width"),
  DBI::Id(table = nicknames_db, column = "nickname")
)

iris_species <- DBI::Id(table = iris_db, column = "species")
nicknames_species <- DBI::Id(table = nicknames_db, column = "species")

query <- glue_sql("
  SELECT {`cols`*}
  FROM {`iris_db`}
  JOIN {`nicknames_db`}
  ON {`iris_species`}={`nicknames_species`}",
  .con = con
)
query
#> <SQL> SELECT `iris`.`sepal_length`, `iris`.`sepal_width`, `nicknames`.`nickname`
#> FROM `iris`
#> JOIN `nicknames`
#> ON `iris`.`species`=`nicknames`.`species`

DBI::dbGetQuery(con, query, n = 5)
#>   sepal_length sepal_width       nickname
#> 1          5.1         3.5 Beachhead Iris
#> 2          4.9         3.0 Beachhead Iris
#> 3          4.7         3.2 Beachhead Iris
#> 4          4.6         3.1 Beachhead Iris
#> 5          5.0         3.6 Beachhead Iris

DBI::dbDisconnect(con)