使用PHP进行SQL查询-从以逗号分隔并链接的一列中获取数据

Question

I have problem with sql query,

I have two tables

** T1 **
ID | Cat
---------
1  | TEXT

2  | TTTT

...

** T2 **

**ID | TEXT | AutID | T1ID  | TEXT2 | TEXT ...**

1    | text | $ID   | 1,2   | text  | text

2    | text | $ID   | 3,4,6 | text  | text

and I need sql query to fetch data from table 2 (t2) from column t1.ID but all data in row1 = 1,2 and in row2 = 3,4,6 and how I can make link from that.

What I have for now is

$query = "SELECT * 
FROM T2, T1
WHERE AutID=$ID 
AND T1.Id=T2.T1ID";

and for link I have use while loop

$catName = $row["Cat"];
$catID = $row["Id"];

echo "<a href=file.php?ID=".$catID . ">" .$catName."</a>

Answer 1

To improve on bumperbox's answer and reduce the queries to the server. Rather than doing multiple queries, you could use an IN statement:

$query2 = "SELECT * FROM T1 WHERE ID in (" . explode(',', $row['T1ID']) . ")";
$res2 = mysql_query($query2) || die(mysql_error());

Answer 2

because you are storing multiple keys in the T1ID column you need to query the data, then split it into separate keys in php, then perform a 2nd query to get the data you want

there are better ways to design a database, if that is a possibility then i would look at a redesign, but if you are stuck with this structure, then you can do the following

$query = "SELECT * FROM T2 WHERE AutID=$ID";

$res = mysql_query($query) || die(mysql_error());

while ($row = mysql_fetch_assoc($res)) {

   $keys = explode(',', $row['T1ID']);

   foreach ($keys as $key) {
      $query2 = "SELECT * FROM T1 WHERE ID=$key";

      $res2 = mysql_query($query2) || die(mysql_error());

      // do what you want with your data now
   }
}