How to connect multiple databases in php at the same time_PHP tutorial

The following is a function that can ensure the connection of different tables in multiple databases. You can save it. It is more practical and useful after testing.

function mysql_oper($oper,$db,$table,$where='1',$limit='10'){
	 	$conn=mysql_connect('localhost','like','admin',true) or mysql_error();
	 	mysql_select_db($db,$conn);
	 	mysql_query("set names utf8");//必须和表单数据字符保持一致
		if($oper=='select'){
		 	$query="select * from `$table` where ".$where." limit ".$limit;
			$res=mysql_query($query,$conn) or die("获取数据失败");
			$arr=array();
			while($row=mysql_fetch_row($res)){
				$arr[]=$row;
			}
			mysql_close($conn);
			return $arr;
		}
	}

The default is query operation, you can modify this code according to your own requirements! , which is the code under the action of the $oper operator

For example, if I now want to query the shop data table under the database named test, and the data with IDs between 10 and 12, then I can call it like the following

mysql_oper('select','test','shop','id>=10 and id