How to display data in two tables php

Question

I have two simple tables T1 and T2 both of datas coming by uploading. I want to display the file_name under a specific user_id.

T1
-------------------------
ID    user_id  admin_id
1     5        11
2     6        11
3     5        11


T2
--------------------------
ID    user_id  file_name 
1     5        orange
2     6        apple
3     5        banana

My problem is it would display twice the echo as below, instead of only once. What is the best way to do this? Do I have to use inner join? Or is it possible to use only 2 for each loop. Sorry for a noob question.

orange banana

Here is my sample:

$test1 = select user_id,admin_id FROM T1;

for($test1 as $key => $value)
{
  $test2 = select user_id,file_type FROM T2;

  foreach($test2 as $key => value2)
  {
    if(test1->user_id==test2->user_id)
    {
      $test2 = select user_id,file_name FROM T2;
      echo $test2->file_name.'<br>';
    }
  }

}

You're talking about sql queries, but you don't seem to execute any sql in your examples. The question is tagged PHP, but the your code example isn't valid PHP. Can you be clearer and fix these problems? — Jon Surrell
– Jon Surrell, Commented Jul 13, 2015 at 11:22
yes you need joins for that.. its not a good practice to use a query inside a loop. you are only exhausting your server — Meenesh Jain
– Meenesh Jain, Commented Jul 13, 2015 at 11:22

Marvin Fischer · Accepted Answer · 2015-07-13 11:14:33Z

1

First, you totally missed the php syntax in your sample (talking about the query strings), secondly there isn't any request to your mysql (or whatever sql) server.

For your SQL command you should read about the JOIN command that exists in SQL http://www.w3schools.com/sql/sql_join.asp Here is a good site to start with it. Its detailed and provides good examples

For your question about inner join: no you need left join (correct me if im wrong) and join on user_id. I won't use 2 queries + loops cause the connection is the slowest thing in a whole database transaction. The command itself will be done in about no time

answered Jul 13, 2015 at 11:14

Marvin Fischer

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