查找和更改表中的值

问题描述：

I have a table with images in SQL database. It looks something like this.

SELECT * FROM eshop_images WHERE fg_idProduct='$id' AND main='1'
+----------+-----+------+--------------+
| idImages | url | main | fg_idProduct |
+----------+-----+------+--------------+
|  1       | x   | 0    |      1       |
|  2       | x   | 1    |      1       |
|  3       | x   | 0    |      1       |
|  4       | x   | 0    |      2       |
|  5       | x   | 0    |      2       |
|  6       | x   | 0    |      2       |
|  7       | x   | 1    |      2       |
+----------+-----+------+--------------+

Each product can only have one main image, but what if I want to set some other image which is 0 as main one?

I have to go through the whole table where fg_idProduct=$id and SET them to null. I don't know how to do this, can somebody help me?

Thanks.

我在SQL数据库中有一个包含图像的表。它看起来像这样。 p> \ n

  SELECT * FROM eshop_images WHERE fg_idProduct ='$ id'AND main ='1'
 + ---------- + ----- + ------ +  -------------- + \ N |  idImages | 网址| 主要|  fg_idProduct | 
 + ---------- + ----- + ------ + -------------- + 
 |  1 |  x |  0 |  1 | 
 |  2 |  x |  1 |  1 | 
 |  3 |  x |  0 |  1 | 
 |  4 |  x |  0 |  2 | 
 |  5 |  x |  0 |  2 | 
 |  6 |  x |  0 |  2 | 
 |  7 |  x |  1 |  2 | 
 + ---------- + ----- + ------ + -------------- + 
  code>  
 
 每个产品只能有一个主图像，但如果我想设置一个0为主要图像的其他图像怎么办？  
 p> 
 
 
我必须遍历整个表，其中fg_idProduct = $ id并将它们设置为null。 我不知道怎么做，有人可以帮帮我吗？ p> 
 
 
谢谢。 p> 
  div>

答

Try this:

UPDATE eshop_images
SET main = 0
WHERE main = 1
AND fg_idProduct = $id

答

UPDATE eshop_images
SET main = 0
WHERE main = 1
AND fg_idProduct = $id

查找和更改表中的值

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