Inserting values in postgres but they are interpreted as column - ruby-on-rails

Question

I am trying to insert some data in my postgres databae like this:
def insert_row(conn, row)
attendee = map_row_to_struct(row)
conn.execute(
<<-SQL
INSERT INTO tmp_attendee_import (email, first_name, last_name)
VALUES("#{attendee.email}", "#{attendee.first_name}", "#{attendee.last_name}");
SQL
)
end
The SQL is evaluated wonderfully as:
INSERT INTO tmp_attendee_import (email, first_name, last_name)
VALUES("myemail#yahoo.com", "Gigel", "Ion");
Yet I get this error:
Failure/Error:
conn.execute(
<<-SQL
INSERT INTO tmp_attendee_import (email, first_name, last_name)
VALUES("#{attendee.email}", "#{attendee.first_name}", "#{attendee.last_name}");
SQL
)
ActiveRecord::StatementInvalid:
PG::UndefinedColumn: ERROR: column "myemail#yahoo.com" does not exist
LINE 2: VALUES("myemail#yahoo.com", "Gigel", "Ion");
^
: INSERT INTO tmp_attendee_import (email, first_name, last_name)
VALUES("myemail#yahoo.com", "Gigel", "Ion");
Anyone has any clue ?

Answer 1

Postgres manual
A string constant in SQL is an arbitrary sequence of characters
bounded by single quotes ('), for example 'This is a string'. To
include a single-quote character within a string constant, write two
adjacent single quotes, e.g., 'Dianne''s horse'. Note that this is not
the same as a double-quote character (").
There is a second kind of identifier: the delimited identifier or
quoted identifier. It is formed by enclosing an arbitrary sequence of
characters in double-quotes ("). A delimited identifier is always an
identifier, never a key word. So "select" could be used to refer to a
column or table named "select", whereas an unquoted select would be
taken as a key word and would therefore provoke a parse error when
used where a table or column name is expected.
TL;DR: Single quotes for string constants, double quotes for table/column names.
BTW, the way you're choosing for inserting records is vulnerable to sql-injection.