使用LIKE将数据从一个表匹配到另一个表

Question

I'm wondering you can match data from one table to another (example below)

What if I wanted to link my second table to the first one and add the id of the city to my headline.

I guess I would need to something like:

 SELECT * FROM headlines where headline LIKE %$city%

And then do an insert everything time I got something returned. But then I would need to repeat my query for the hundred of cities I have every time I add a new headline.

    First Table (Cities) | Second Table (Headlines)
    ______________________________________________________
    id: 1 name: New-York | Something happened in New-York
    id: 2 name: LA       | Something else happened in LA
                         | Somehting happened in LA and New-York

Can anybody point me to whatever I should be looking into to do this ?

Answer 1

You would use a join clause with a like condition:

 SELECT h.*, c.cities
 FROM headlines h join
      cities c
      on h.headline like concat('%', c.city, '%')

The key is getting the wildcard parameters in the pattern, using concat() .

By the way, this will do a nest-loop query, which will not perform very well. Because of the like condition, indexes will not help improve performance.

A better approach is to build a full text index on the headline column and use match for the comparison. This will also help prevent conflicts like "London" matching "Londonderry".

And, in your example LA is particularly problematic, because many words contain LA . You could try something like:

      on concat(' ', replace(replace(replace(h.headline, ',', ' '), ':', ' '), '.', ' '), ' ') like
               concat('% ', c.city, ' %')

That is, replace punctuation with spaces, add a space at the beginning and end of the headline, and then look for the city name surrounded by spaces. This prevents a match between "LA" and "AtLAnta" (caps only for emphasis).

Answer 2

you can try this

$sql = "SELECT * FROM cities";
$res_mysql=mysql_query($sql);  
   while($arr=mysql_fetch_array($res_mysql)){
      while(mysql_fetch_array($res_mysql_like)){
          $update= "UPDATE `Headlines` SET `id` ='".$arr[1]."'
          WHERE `headline LIKE %$arr[1]%";
      mysql_query($update)
      or die(mysql_error());
      }
   }

you need to select fisrt id fron city table and check if appear in headline table, then do the same white 2 id of table cities.

i hope this can help you, maybe i didn't understand very well the problem, mi english level isn't very good.