length
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Returns the length of the input array.
Syntax
length( <array> )Returns
The data type of the returned value is INTEGER.
Examples
Here is a simple example:
SELECT length([1, 2, 3]);+-------------------+
| length([1, 2, 3]) |
+-------------------+
| 3 |
+-------------------+Here is a slightly more complex example, this time using array data type:
CREATE TABLE colors (v array);
VALUES
('[{"r":255,"g":12,"b":0},{"r":0,"g":255,"b":0},{"r":0,"g":0,"b":255}]'),
('[{"r":255,"g":128,"b":0},{"r":128,"g":255,"b":0},{"r":0,"g":255,"b":128},{"r":0,"g":128,"b":255},{"r":128,"g":0,"b":255},{"r":255,"g":0,"b":128}]')
SELECT parse_json($0)::array
INSERT INTO colors;Retrieve the length for each array:
FROM colors SELECT length(v);+-----------+
| length(v) |
+-----------+
| 3 |
| 6 |
+-----------+Retrieve the last element of each array:
FROM colors SELECT v[length(v)-1];+-------------------------+
| v[length(v) - 1] |
+-------------------------+
| {"b":255,"g":0,"r":0} |
| {"b":128,"g":0,"r":255} |
+-------------------------+