table_keyword_content| keyword_id | content_id |
+------------+------------+
| 1 | 1 |
| 2 | 1067 |
| 3 | 1068 |
| 3 | 1069 |
| 3 | 1070 |
| 3 | 1071 |
| 3 | 1072 |如果我select * from table_keyword_content group by keyword_id的话,结果就是| keyword_id | content_id |
+------------+------------+
| 1 | 1 |
| 2 | 1067 |
| 3 | 1068 |可我只是group by ,为什么会有这种结果?不是应该按分组都列出来吗?
+------------+------------+
| 1 | 1 |
| 2 | 1067 |
| 3 | 1068 |
| 3 | 1069 |
| 3 | 1070 |
| 3 | 1071 |
| 3 | 1072 |如果我select * from table_keyword_content group by keyword_id的话,结果就是| keyword_id | content_id |
+------------+------------+
| 1 | 1 |
| 2 | 1067 |
| 3 | 1068 |可我只是group by ,为什么会有这种结果?不是应该按分组都列出来吗?
默认排序select * from table_keyword_content