php - 尝试使用php创建表时出错

Question

我是php新手，我正在尝试使用mysql创建一个表。当我运行我编写的php代码时，它会说：

Warning: mysqli_select_db() expects parameter 1 to be mysqli, string given in /home/engelsmj/public_html/Table/CreateTable.php on line 16
Warning: mysqli_query() expects at least 2 parameters, 1 given in /home/engelsmj/public_html/Table/CreateTable.php on line 23
Notice: Undefined variable: sql in /home/engelsmj/public_html/Table/CreateTable.php on line 25
Warning: mysqli_query(): Empty query in /home/engelsmj/public_html/Table/CreateTable.php on line 25 

Error creating table:

I believe it is connecting to mysql, but is having an error with actually creating the table. I've worked through my code several times but I can't figure out what's wrong with it and why it won't create my table. Thanks for any help with this.

<?php
error_reporting(E_ALL);
ini_set("display_errors", 1);

    $con=mysqli_connect("*******","******","*******");
    if (mysqli_connect_errno()) {
      echo "Failed to connect to MySQL: " . mysqli_connect_error();
    }

    mysqli_select_db("*****", $con);

    mysqli_query("CREATE TABLE Friends(
    idNumber INT NOT NULL AUTO_INCREMENT,  
    Name varchar(30),
    Phone varchar(30), 
    Age int,
    PRIMARY KEY (idNumber))");

    if (mysqli_query($con,$sql)) {
     echo "Friends table created successfully";
    } else {
      echo "Error creating table: " . mysqli_error($con);
    }
    mysqli_close($con);

?>

Answer 1

必须切换这些值：

//Wrong 
mysqli_select_db("*****", $con);

//Right
mysqli_select_db($con, "*****");

至于查询，您必须添加$sql而不是mysqli_query，因为稍后在if语句中会这样做：

$sql = "CREATE TABLE Friends(
idNumber INT NOT NULL AUTO_INCREMENT,  
Name varchar(30),
Phone varchar(30), 
Age int,
PRIMARY KEY (idNumber))";