Oracle SQL Variable: SELECT with STRING list of values in an IN clause

Question

This works correctly:

DEFINE numbers = '1,2,3,4,5';
SELECT * FROM table1 WHERE items IN (&numbers);

As does this:

SELECT * FROM table1 WHERE items IN ('a','b','c','d'); error

This returns a snytax ERROR:

DEFINE letters = 'a','b','c','d';
SELECT * FROM table1 WHERE items IN (&letters);  -- result syntax ERROR

How can I use a WHERE ... IN clause using a list of strings created by DEFINE?

Solution

Enclose the DEFINE value in double-quotes:

define letters = "'a','b','c','d'"

set verify on

select * from dual where dummy in (&letters);

old   1: select * from dual where dummy in (&letters)
new   1: select * from dual where dummy in ('a','b','c','d')

no rows selected

Note that the challenge is really how to DEFINE a multi-word string, as it's the same problem:

SQL> define letters = I love kittens
SQL> define letters
DEFINE LETTERS         = "I" (CHAR)

SQL> define letters = 'a','b','c','d'
SQL> define letters
DEFINE LETTERS         = "a" (CHAR)

Double-quotes fix that:

SQL> define letters = "I love kittens"
SQL> define letters
DEFINE LETTERS         = "I love kittens" (CHAR)

Just for completeness, the other way to set a define variable is from a select statement using the column new_value approach. Historically this was provided for setting page headings dynamically in SQL*Plus reports, but it's handy in scripts. (It's also the only way to set the type to number, not that it makes any difference.)

SQL> col letters new_value letters
SQL> select q'{'a','b','c','d'}' as letters from dual;

LETTERS
---------------
'a','b','c','d'

1 row selected.

SQL> def letters
DEFINE LETTERS         = "'a','b','c','d'" (CHAR)

SQL> select 123.456 as letters from dual;

   LETTERS
----------
   123.456

1 row selected.

SQL> def letters
DEFINE LETTERS         =    123.456 (NUMBER)