| --- |
| { |
| "title": "ARRAY_AGG", |
| "language": "en" |
| } |
| --- |
| |
| ## Description |
| |
| Concatenates the values (including null values) in a column into an array, which can be used for pivoting rows into columns. |
| |
| ## Syntax |
| |
| ```sql |
| ARRAY_AGG(<col>) |
| ``` |
| |
| ## Parameters |
| |
| | Parameter | Description | |
| | -- | -- | |
| | `<col>` | An expression that determines the values to be placed into the array (usually column names). | |
| |
| ## Return Value |
| |
| Returns a value of ARRAY type.Special cases: |
| |
| - The order of elements in the array is not guaranteed. |
| - Returns the array generated by the conversion. The element type in the array is consistent with the type of col. |
| |
| |
| ## Example |
| |
| ```sql |
| select * from test_doris_array_agg; |
| ``` |
| |
| ```text |
| +------+------+ |
| |
| | c1 | c2 | |
| |
| +------+------+ |
| |
| | 1 | a | |
| |
| | 1 | b | |
| |
| | 2 | c | |
| |
| | 2 | NULL | |
| |
| | 3 | NULL | |
| |
| +------+------+ |
| ``` |
| |
| ```sql |
| select c1, array_agg(c2) from test_doris_array_agg group by c1; |
| ``` |
| |
| ```text |
| +------+-----------------+ |
| |
| | c1 | array_agg(`c2`) | |
| |
| +------+-----------------+ |
| |
| | 1 | ["a","b"] | |
| |
| | 2 | [NULL,"c"] | |
| |
| | 3 | [NULL] | |
| |
| +------+-----------------+ |
| ``` |
| |
