This set of classes and generics make it possible to flexibly deal with SQL
escaping needs. By default, any user supplied input to a query should be
escaped using either
depending on whether it refers to a table or variable name, or is a literal
These functions return an object of the
which tells DBI functions that a character string does not need to be escaped
anymore, to prevent double escaping.
SQL class has associated the
SQL() constructor function.
SQL(x)dbQuoteIdentifier(conn, x, ...)dbQuoteString(conn, x, ...)
- A character vector to label as being escaped SQL.
- A subclass of
DBIConnection, representing an active connection to an DBMS.
- Other arguments passed on to methods. Not otherwise used.
An object of class
DBI provides default generics for SQL-92 compatible quoting. If the database
uses a different convention, you will need to provide your own methods.
Note that because of the way that S4 dispatch finds methods and because
SQL inherits from character, if you implement (e.g.) a method for
dbQuoteString(MyConnection, character), you will also need to
dbQuoteString(MyConnection, SQL) - this should simply
x unchanged. If you implement your own method, make sure to convert NA to NULL (unquoted).
# Quoting ensures that arbitrary input is safe for use in a query name <- "Robert'); DROP TABLE Students;--" dbQuoteString(ANSI(), name) dbQuoteIdentifier(ANSI(), name) # NAs become NULL dbQuoteString(ANSI(), c("x", NA)) # SQL vectors are always passed through as is var_name <- SQL("select") var_name dbQuoteIdentifier(ANSI(), var_name) dbQuoteString(ANSI(), var_name) # This mechanism is used to prevent double escaping dbQuoteString(ANSI(), dbQuoteString(ANSI(), name))