增量所有+1行其中一行大於

Question

我有這些領域

+------------+-------------+----------------+----------+-------------+ 
| channel_id | channel_row | content_digest | seriesid | provider_id | 
+------------+-------------+----------------+----------+-------------+ 
|  296 |   0 | SVT::2258207 | NULL  | NULL  | 
|  296 |   1 | SVT::2354966 | NULL  | NULL  | 
|  296 |   2 | SVT::2287450 | NULL  | NULL  | 
|  296 |   3 | SVT::2269811 | NULL  | NULL  | 
+------------+-------------+----------------+----------+-------------+ 

而我想要做的是增量，說所有的channel_row與+1，其中channel_row is <= 1，這意味着1和2 3應成爲2和3,4和0應保持不變...

但是，這是不行的，至少不會在1 SQL查詢，我現在有：

UPDATE channel_row SET channel_row = channel_row+1 WHERE channel_id = '296' AND channel_row <= '1' ORDER BY channel_row DESC 

但是必須有某種方式，對吧？或者這實際上是不可能的？

Answer 1

你在那裏說法是錯誤的：

AND channel_row <= '1' 

必須

AND channel_row >= '1' 

Answer 2

你有一個錯誤的情況下，<=應該>=

UPDATE channel_row 
SET channel_row = channel_row+1 
WHERE channel_id = '296' 
AND channel_row >= '1' ORDER BY channel_row DESC 

下面是一個簡單的測試用例

mysql> create table test (id int , val int); 
Query OK, 0 rows affected (0.16 sec) 

mysql> insert into test values (1,0),(1,1),(1,2),(1,3); 
Query OK, 4 rows affected (0.05 sec) 
Records: 4 Duplicates: 0 Warnings: 0 

mysql> select * from test ; 
+------+------+ 
| id | val | 
+------+------+ 
| 1 | 0 | 
| 1 | 1 | 
| 1 | 2 | 
| 1 | 3 | 
+------+------+ 
4 rows in set (0.00 sec) 

mysql> update test set val=val+1 where id = 1 and val > 0 ; 
Query OK, 3 rows affected (0.02 sec) 
Rows matched: 3 Changed: 3 Warnings: 0 

mysql> select * from test ; 
+------+------+ 
| id | val | 
+------+------+ 
| 1 | 0 | 
| 1 | 2 | 
| 1 | 3 | 
| 1 | 4 | 
+------+------+ 
4 rows in set (0.00 sec) 

Answer 3

您的<=是不正確的。你想更新所有更高的0，所以它必須是channel_row > 0。另外，數量不宜在''

UPDATE table_name 
SET channel_row = channel_row + 1 
WHERE channel_id = 296 AND channel_row > 0 

的ORDER BY聲明不需要