MySQL从多个相同的表中选择并使用php随机显示结果

Question

Hello I would like to query multiple identical tables in my db which has different prefixes and than display the results randomly but somehow I need to track the origin of the item and I couldn't figure out how

I do the query like this because I don't have access to information_schema

$query = "SHOW TABLES FROM mydb WHERE RIGHT( tables_in_mydb, 5 ) = 'table'";
$res = mysql_query($query);
$num = mysql_num_rows($res);

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

$numbers = explode('_', $row[0]);

  if($num > 0) {
    $q = "SELECT `this`, `that`, `something` FROM ".$numbers[0]."_idetinticaltables"; // :)
    $r = mysql_query($q);
    while($c = mysql_fetch_array($r)) {
       /*display the results randomly with an identifier where the come from*/
    }
  }
}

Answer 1

您可以使用ORDER BY RAND（）对其进行随机排序

Answer 2

$aa=array()   
while($c = mysql_fetch_array($r)) 
{
   /*display the results randomly with an identifier where the come from*/
   $aa[]=$c;
}
echo $aa; // print "Array"

Answer 3

The following might work:

1. Get the list of the tables you're interested in. You already do that.

2. Create a UNION of multiple SELECT statements . Each SELECT statement differs for the table being selected from and you add a column set to the name of the table (so you can identify it later):

    (SELECT *, TABLENAME = 'first_name_of_table' FROM first_name_of_table ...) UNION (SELECT *, TABLENAME = 'second_name_of_table' FROM second_name_of_table ...) UNION ... ORDER BY RAND() LIMIT 10; 

3. Because it is a UNION you can randomize the whole order then. See How can i optimize MySQL's ORDER BY RAND() function? because it is not that trivial to do well, the example above is only to have an ORDER BY and LIMIT clause placed there. With many entries in your tables, it will kill your server.