函数，SQL连接和全局变量 [英] Functions, SQL Connects and Global Variable

问题描述

连接和关闭数据库有什么问题吗？通过调用下面的函数使用两个

 <$ c $之间的mysql_query和mysql_fetch_array命令c><？php 
 
函数dbconnect（）
 {
 $ sql =localhost; 
 $ username =------; 
 $ password =-----; 
 $ connection = mysql_connect（$ sql，$ username，$ password）或
 die（unwable to cct）; 
 $ databse = mysql_select_db（-------，$ connection）; 
全球$连接; 
} 
 
函数close（）
 {
 global $ connection; 
 mysql_close（$ connection）; 
} 
 
 dbconnect（）; 
 $ query =某些SQL语句; 
 $ data = mysql_query（$ query，$ connection）; -  L1 
 while（mysql_fetch_assoc（$ data））
 {
 // echo something 
} 
 close（）; 
？> 
  

目前，我收到一个错误消息，说L1的$ connection需要是一个资源，但是一个BOOL。如果我在那里给出一个死亡陈述，就会触发相同的陈述。我不知道什么是错的。请发现任何可能的错误。我必须从编码中休假，并在一段时间后回来。

谢谢，关于

解决方案

您必须使用全局关键字 / em>分配 $连接变量。否则，你在函数内声明一个本地的 $ connection ，然后调用对不存在的全局 $ connection 。在其他函数中，使用了不存在的全局变量。

 函数dbconnect（）
 {
 // Global首先要确保后面的$连接是全局的
 //而不是这个函数本地的新连接
 global $ connection; 
 
 $ sql =localhost; 
 $ username =------; 
 $ password =-----; 
 //现在这会修改全局$连接
 $ connection = mysql_connect（$ sql，$ username，$ password）或死（unwable to cct）; 
 $ databse = mysql_select_db（-------，$ connection）; 
} 
  

更具可读性的是使用 $ GLOBALS array：

 函数dbconnect（）
 {
 $ sql =localhost ; 
 $ username =------; 
 $ password =-----; 
 
 //使用$ GLOBALS超全局数组
 $ GLOBALS ['connection'] = mysql_connect（$ sql，$ username，$ password）或死（unwable to cct）; 
 $ databse = mysql_select_db（-------，$ GLOBALS ['connection']）; 
} 
  

最棒的是返回 $ connection from dbconnect（）并在其他函数中使用该值：

 函数dbconnect（）
 {
 $ sql =localhost; 
 $ username =------; 
 $ password =-----; 
 $ connection = mysql_connect（$ sql，$ username，$ password）或
 die（unwable to cct）; 
 $ databse = mysql_select_db（-------，$ connection）; 
 
 //从函数
返回$ connection; 
} 
 
 //调用为
 $ connection = dbconnect（）; 
 //并定义您的其他函数以接受$ connection作为参数
  

Is there anything wrong with connecting and closing to a database by calling the function below with the mysql_query and mysql_fetch_array commands between the two

<?php

function dbconnect()
{   
    $sql = "localhost"; 
    $username = "------";
    $password = "-----";
    $connection = mysql_connect($sql, $username, $password) or 
    die("unwable to cct");
    $databse = mysql_select_db("-------", $connection); 
    global $connection;
}

function close()
{
    global $connection;
    mysql_close($connection);
}

dbconnect();
$query = "Some SQL Statement";
$data = mysql_query($query, $connection); - L1
while (mysql_fetch_assoc($data))
{
  //echo something 
}
close();
?>

At present, I am getting an error saying that $connection at L1 needs to be a resource but is a BOOL. If I give a die statement there, the same is triggered. I have no idea what is wrong. Please spot any errors you can. I have to take a sabbatical from coding and I am back after a while.

Thanks & regards

解决方案

You must use the global keyword before assigning the $connection variable. Otherwise, you declare a local $connection inside the function and then call a reference to the yet non-existent global $connection. In the other functions, that non-existent global is used.

function dbconnect()
{   
    // Global first to be sure the subsequent $connection is the global
    // rather than a new one local to this function
    global $connection;

    $sql = "localhost"; 
    $username = "------";
    $password = "-----";
    // Now this modifies the global $connection
    $connection = mysql_connect($sql, $username, $password) or die("unwable to cct");
    $databse = mysql_select_db("-------", $connection); 
}

More readable would be to use the $GLOBALS array:

function dbconnect()
{   
    $sql = "localhost"; 
    $username = "------";
    $password = "-----";

    // Using the $GLOBALS superglobal array
    $GLOBALS['connection'] = mysql_connect($sql, $username, $password) or die("unwable to cct");
    $databse = mysql_select_db("-------", $GLOBALS['connection']); 
}

Best of all would be to return $connection from dbconnect() and use that value in other functions:

function dbconnect()
{   
    $sql = "localhost"; 
    $username = "------";
    $password = "-----";
    $connection = mysql_connect($sql, $username, $password) or 
    die("unwable to cct");
    $databse = mysql_select_db("-------", $connection);

    // Return from the function
    return $connection; 
}

// call as 
$connection = dbconnect();
// and define your other functions to accept $connection as a parameter

这篇关于函数，SQL连接和全局变量的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！