R: SQL quoting

SQL {DBI} | R Documentation

## SQL quoting

### Description

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 `dbQuoteIdentifier()` or `dbQuoteString()` depending on whether it refers to a table or variable name, or is a literal string. These functions may return an object of the `SQL` class, which tells DBI functions that a character string does not need to be escaped anymore, to prevent double escaping. The `SQL` class has associated the `SQL()` constructor function.

### Usage

    SQL(x)

### Arguments

`x` | A character vector to label as being escaped SQL.
`...` | Other arguments passed on to methods. Not otherwise used.

### Value

An object of class `SQL`.

### Implementation notes

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 implement `dbQuoteString(MyConnection, SQL)` - this should simply return `x` unchanged.

### Examples

    dbQuoteIdentifier(ANSI(), "SELECT")
    dbQuoteString(ANSI(), "SELECT")

    # 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(), "SELECT"))

[Package DBI version 0.6-1 Index]