如何在Postgres中查询数组存储列，（数组交集）

Question

I have a table which contains value in array something like this.

id | contents_id
 1 | [1, 3, 5]
 2 | [1, 2]
 3 | [3, 4, 6]
 4 | [2, 5]

How to write a query array eg [1, 2] such that it check value of array not array as a whole ?

If any common value of array is found get all tuples.

If [1, 2] is queried it must fetch id => 1, 2, 4 from above table as it contains 1 or 2 .

Answer 1

Consider using the intarray extension. It provides a && operator for testing integer array overlapping. Here is a fiddle, with an example.

select id from test where ARRAY[1,2] && contents_id;

Though you can query it with the operator, I think it will be better to make a junction table with integer IDs.

Answer 2

On 1-D int arrays && operator arrayoverlap is the fastest as @LaposhasúAcsa suggested.

so my answer stands only if arrayoverlap is not avaliable or want to work with anything other than one dimensional integer arrays.

Check UNNEST https://www.postgresql.org/docs/current/static/functions-array.html

CREATE TABLE t45407507 (
   id SERIAL PRIMARY KEY 
  ,c int[]
);
insert into t45407507 ( c) values
    (ARRAY[1,3,5])
  , (ARRAY[1,2])
  , (ARRAY[3,4,6])
  , (ARRAY[2,5]);

select DISTINCT id from 
  (SELECT id,unnest(c) as c
  from t45407507) x 
where x.c in (1,2);

Can be shortened with LATERAL join

select DISTINCT id from
   t45407507 x,unnest(c) ec
where ec in (1,2);

The comma (,) in the FROM clause is short notation for CROSS JOIN . LATERAL is assumed automatically for table functions like unnest() .

Rewrite WHERE to use ARRAY as parameter

SELECT DISTINCT id FROM
  t45407507 x,unnest(c) ec
WHERE ec = ANY(ARRAY[1,2]);