# How to Compare Arrays in PostgreSQL

The **equality operators** (`=`

, `<>`

) do an exact element-by-element comparison.

```
select
array[1,2,3] = array[1,2,4] as compare1, -- arrays are equal
array[1,2,3] <> array[1,2,4] as compare2; -- arrays are not equal
```

```
compare1 | compare2
----------+----------
f | t
```

The **ordering operators** (`>`

, `<`

, `>=`

, `<=`

) also compare each element in an array in order. Results are based on the first different pair of elements, not the sizes of the arrays.

```
select
array[1,2,5] >= array[1,2,4] as compare1,
array[1,2,5] <= array[1,2,4,5] as compare2;
```

```
compare1 | compare2
----------+----------
t | f
```

Then there are the **containment operators** (`@>`

, `<@`

). They are casually called "bird operators", well, because `@>`

looks like a bird. An array is said to be contained in another array if each of its unique elements is also present in the other array.

```
-- This reads as array['a', 'b', 'c'] contains array['a', 'b', 'b', 'a']
select array['a', 'b', 'c'] @> array['a', 'b', 'b', 'a'] as contains;
```

```
contains
----------
t
```

```
-- this reads as array[1, 1, 4] is contained by array[4, 3, 2, 1]
select array[1, 1, 4] <@ array[4, 3, 2, 1] as is_contained_by;
```

```
is_contained_by
-----------------
t
```

Lastly, there is the **overlap operator** (`&&`

). Arrays that have elements in common are called overlapping arrays. To check if two arrays overlap, use the `&&`

operator:

```
select
array[1, 2] && array[2, 3] as overlap1,
array[1, 2] && array[3, 4] as overlap2;
```

```
overlap1 | overlap2
----------+----------
t | f
```

Spread the word

Tweet