php批量修改表结构实例

<?phpset_time_limit(0);$con = mysql_connect("localhost", "root", "root");$dbname = "db";if ($con) { if (mysql_select_db($dbname, $con)) {  $sql = "show tables like 'pre_tb_%'";  $ret = mysql_query($sql);  while($row = mysql_fetch_assoc($ret)){   $info1[] = $row;  }  foreach ($info1 as $v) {   $chidarr1[] = substr($v['Tables_in_multiopen (pre_tb_%)'],7);//获取标记号  }  foreach ($chidarr1 as $val) {   $tabname = 'stat_adclick_'.$val;   $sql = "alter table $tabname add column c2 int default 0 after p";   mysql_query($sql);   $sql = "alter table $tabname DROP PRIMARY KEY";   mysql_query($sql);   $sql = "alter table $tabname add primary key(c2,p)";   mysql_query($sql);   $sql = "alter table $tabname drop index old_index";   mysql_query($sql);   $sql = "create index idx_newincex on $tabname (c2,p)";   mysql_query($sql);  } }}mysql_close($con);?>