如何比较PHP中两个表中的两个字段？

Question

Table_1

ID | Username
 1   John
 2   Mike
 3   Chase
 4   Shane

Table_2

 ID | Username
 1  | John
 2  | Kenny
 3  | Chase
 4  | Shane

I want to get ID from Table_1. Then find that ID in table_2. Then i need it to look at the field Username in both tables. and if they match do nothing, If they don't match then update it to the username in Table_2 and run some code (like email me)

I need to to check every row in Table_1 everytime I run the script.

Answer 1

You have to use INNER JOIN in case to find the matching ID in both the tables and if you got one then update.

$sql = mysql_query("SELECT table_1.id as id_one,table_1.name as name_one,table_2.name as name_two FROM table_1 INNER JOIN table_2 ON (table_1.id = table_2.id)") or die(mysql_error());

    if(mysql_num_rows($sql) > 0)
    {
         while($fetch = mysql_fetch_assoc($sql))
         {
               if($fetch['name_one'] != $fetch['name_two'])
               {
                     // UPDATE table_1 'name' FIELD

                       mysql_query("UPDATE table_1 SET name = '".$fetch['name_two']."' WHERE id = ".$fetch['id_one']) or die(mysql_error());

                          // DO WHATEVER YOU WANT
               }

         }
    }