group_concat 的用法
2020年3月19日原始表格
| category_id | content_id |
| 1 | 2 |
| 2 | 5 |
| 3 | 6 |
| 4 | 1 |
| 4 | 7 |
| 3 | 2 |
| 2 | 12 |
| 1 | 13 |
| 3 | 15 |
| 3 | 17 |
| 2 | 23 |
| 4 | 26 |
| 1 | 55 |
执行sql语句
|
1 |
select category_id , group_concat(content_id) from `category_has_contents` group by category_id |
结果
| category_id | group_concat(content_id) |
| 1 | 16,24,25,27,28,29,36,44,52,300,304,313,318,319,321,325,331,341,348,3450,451,452,453,454,462,465,467,468,482,484,488,497 |
| 2 | 0,257,263,5,461,471,486,489,4,366,376,378,383,389,392,398,401,402,404,410,413,414,422,427,429,430,438,439,441,445,449,456,457,463,469,470,471,489,492,494,496,498 |
| 3 | 3,4,6,17,408,417,419,423,431,433,435,437,442,444,447,448,459,460,466,476,478,485,491,493,495,500,501 |
