如何在一个查询中更新多行（使用for循环）

Question

For example, I have two data on my table:

| ID | Name | Age |

---

| 1 | Steve | 25 |
| 2 | Bob | 28 |

When i updating one value (for example: change "Bob" to "George"), it changes all value. This is the result:
| ID | Name | Age |

---

| 1 | George | 28 |
| 2 | George | 28 |

How to updating multiple rows in one query? To collect values, I use for loop like this:

<?php
...
$id_array = $_POST['id'];
$name_array = $_POST['name'];
$age_array = $_POST['age'];

$id = array();
$name = array();
$age = array();

for ($i = 0; $i < count($id_array); $i++) {
//count($id_array) --> if I input 4 fields, count($id_array) = 4)

   $id[] = mysql_real_escape_string($id_array[$i]);
   $name[] = mysql_real_escape_string($name_array[$i]);
   $age[] = mysql_real_escape_string($age_array[$i]);                    
}
mysql_query("UPDATE member SET name = '$name', age = '$age' WHERE id = '$id'");
}
...
?>

Can you help me? Thank you.

Answer 1

Construct your query within the loop:

<?php
...
$id_array = $_POST['id'];
$name_array = $_POST['name'];
$age_array = $_POST['age'];

for ($i = 0; $i < count($id_array); $i++) {
//count($id_array) --> if I input 4 fields, count($id_array) = 4)

   $id = mysql_real_escape_string($id_array[$i]);
   $name = mysql_real_escape_string($name_array[$i]);
   $age = mysql_real_escape_string($age_array[$i]);

   $query .= "UPDATE member SET name = '$name', age = '$age' WHERE id = '$id';";
}

mysql_query($query);
}
...
?>

Hope that helps..!

Answer 2

Answer to your Question
MySQL updates all rows matching the WHERE clause, so to update multiple rows with the same value, you should use a condition matching all rows. To update all rows, dont set any where clause. To update multiple rows with different values, you can't, use several queries.

Answer to your issue
In your code, $id, $name and $age are arrays so you can not use it in a string, this will not work. You should do the update in your FOR loop. I advise you to try to respect resource oriented principe that all properties are assigned to their item (with associative array or object). If you dont check the result, you could do all queries in one using a semi-colon.