MYSQL，PHP更新表

Question

我扫描了互联网两天，没有任何结果。 我尝试使用与前面的单元格相同的值更新MYSQL表中的空单元格：

+-------+      +-------+
|ID |VAL|      |ID |VAL|
+-------+      +-------+
| 1 | 7 |      | 1 | 7 |
| 2 |   |      | 2 | 7 |
| 3 |   |      | 3 | 7 |
| 4 | 4 |      | 4 | 4 |
| 5 | 5 |after:| 5 | 5 |
| 6 |   |      | 6 | 5 |
| 7 |   |      | 7 | 5 |
| 8 | 8 |      | 8 | 8 | 
| 9 | 3 |      | 9 | 3 |
|10 |   |      |10 | 3 |
+-------+      +-------+

Answer 1

这是我的解决方案，希望能对您有所帮助

 $old_datas = [ [1,7], [2,null], [3,null], [4,4], [5,5], [6,null], [7,null] ]; // get old data from table as array : select * from table where 1 order by id ASC; // set default pre value $pre_val = 0; foreach( $old_datas as $old_data ){ if( !$old_data['VAL'] ){ // update table set VAL=$pre_val where id=$old_data['ID'] }else{ $pre_val = $old_data['VAL']; } } 

Answer 2

感谢您的回答，这终于成功了

UPDATE TABLE
SET VAL = (@n := COALESCE(VAL, @n))
ORDER BY ID