列表列的SQL WHERE子句

Question

How can I specify a WHERE clause, so that it returns a row if there is an intersection between the column's value (list of strings) and another list of strings provided? Something like:

SELECT id, names
FROM table
WHERE ANY(names) = ANY(('John', 'Alice', 'Bob'))

So if the value names column is, eg ['George', 'Bob'] , the row should be returned.

Answer 1

You should really use arrays or a table of records for this .

You can work around your design by splitting strings into arrays at runtime and using PostgreSQL's array features .

SELECT id, names
FROM table
WHERE string_to_array(names, ',') && ARRAY['John', 'Alice', 'Bob'];

If your comma separated values have spaces, etc, you might want regexp_split_to_array instead of string_to_array .

Answer 2

If you really can't change your design (which I would recommand, as mentionned by Craig Ringer)

You may use regexp_split_to_array

 SELECT id, names
    from (
    SELECT 
          id,
          names,
          regexp_split_to_table(names, ', ') as splitted_value
    from <yourTable>) t
    where splitted_value in ('John', 'Alice', 'Bob')
    group by id, names;

or more complicated, with your sample

SELECT id, names
    from (
    SELECT 
          id,
          names,
          regexp_split_to_table(replace(replace(names, '[''', ''), ''']', ''), ''', ''') as splitted_value

    from <yourTable>) t
    where splitted_value in ('John', 'Alice', 'Bob')
    group by id, names;

Another ugly way, using some json functions (as your column datas look like json)

"Detail" : I'm not a postgresql expert, and less than all in json datas part. So there may be much better way to do this.

select id, names 
from
 (select 
    id, 
    names,
    replace(cast(json_array_elements(cast(replace(names, '''', '"') as json)) as text), '"', '') as elem
  from <yourTable>) t
where elem in ('George', 'Bob');

Answer 3

You can generate your own function which will mimic MYSQL`s FIND_IN_SET

CREATE OR REPLACE FUNCTION find_in_set(str text, strlist text)
RETURNS int AS $$
SELECT i
   FROM generate_subscripts(string_to_array($2,','),1) g(i)
  WHERE (string_to_array($2, ','))[i] = $1
  UNION ALL
  SELECT 0
  LIMIT 1
$$ LANGUAGE sql STRICT;

http://okbob.blogspot.ro/2009/08/mysql-functions-for-postgresql.html