spec_sql_quote_string
Value
dbQuoteString() returns an object that can be coerced to character,
of the same length as the input.
For an empty character vector this function returns a length-0 object.
When passing the returned object again to dbQuoteString()
as x
argument, it is returned unchanged.
Passing objects of class DBI::SQL should also return them unchanged.
(For backends it may be most convenient to return DBI::SQL objects
to achieve this behavior, but this is not required.)
Specification
The returned expression can be used in a SELECT ... query,
and for any scalar character x the value of
dbGetQuery(paste0("SELECT ", dbQuoteString(x)))[[1]]
must be identical to x,
even if x contains
spaces,
tabs,
quotes (single
or double),
backticks,
or newlines
(in any combination)
or is itself the result of a dbQuoteString() call coerced back to
character (even repeatedly).
If x is NA, the result must merely satisfy is.na().
The strings "NA" or "NULL" are not treated specially.
NA should be translated to an unquoted SQL NULL,
so that the query SELECT * FROM (SELECT 1) a WHERE ... IS NULL
returns one row.
Failure modes
Passing a numeric,
integer,
logical,
or raw vector,
or a list
for the x argument raises an error.
See also
Other sql specifications:
spec_sql_append_table,
spec_sql_create_table,
spec_sql_exists_table,
spec_sql_list_fields,
spec_sql_list_objects,
spec_sql_list_tables,
spec_sql_quote_identifier,
spec_sql_quote_literal,
spec_sql_read_table,
spec_sql_remove_table,
spec_sql_unquote_identifier,
spec_sql_write_table