Question

php 数据库 为什么我明明建了数据库，却老是提示No database selected?

<?php
$con = mysql_connect("localhost","","");
if (!$con)
{
die('Could not connect: ' . mysql_error());
}
if (mysql_query("CREATE DATABASE m",$con))
{
echo "Database created";
}
else
{
echo "Error creating database: " . mysql_error();
}

mysql_select_db("m", $con);
$sql = "CREATE TABLE person
(
FirstName varchar(15),
LastName varchar(15),
Age int
)";
mysql_query($sql,$con);

$sql="INSERT INTO person (FirstName, LastName, Age)
VALUES
('$_POST[firstname]','$_POST[lastname]','$_POST[age]')";

if (!mysql_query($sql,$con))
{
die('Error: ' . mysql_error());
}
echo "1 record added";

mysql_close($con)
?>

Answer 1

数据库的连接应该是这样写的:$con = mysql_connect("主机名字或者是IP","用户名","密码");如果你以前创建过用户名和密码,你的连接是 :$con = mysql_connect("localhost","用户名","密码");如果你没有创建过用户,你就要这样写,$con = mysql_connect("localhost","root","");你先按照这样的改法试试看.