php+；mysql\u num\u行问题？

我有一个简单的sql语句，我想根据返回的行数执行不同的操作

$result_lists = mysql_num_rows(mysql_query("SELECT * FROM db_table"));
    //To see the number returned
    print_r($result_lists);

    switch($result_lists) {
         case($result_lists == 0):
         //To prove which option is actually happening 
         print_r('lists==0: '.$result_lists);  
         break;

         case($result_lists > 1):
         //To prove which option is actually happening 
         print_r('lists>1: '.$result_lists);
         break;

         case($result_lists == 1):
         //To prove which option is actually happening 
         print_r('lists==1: '.$result_lists);  
         break;
    }

如果找到一行或多行，则使用正确的大小写，但是，如果返回零行，则出于某种原因执行（>1）大小写

有人能看出哪里出了问题吗

谢谢你的建议

---

谢谢。

返回零或null，您有支票

case($result_lists == 0 or null):

或许

 case(empty($result_lists)):

---

返回零或null，您必须进行检查

case($result_lists == 0 or null):

或许

 case(empty($result_lists)):

---

你不应该那样使用开关

switch($var)
{
    case 1:
        //Some stuff
        break;
    case 2:
        //Some stuff
        break;
    default:
        break;
}

这是正确的做法。用ifs和ELSE去做，yadayda！你的虫子会消失

---

为什么?？因为

case

不是用来计算语句的。它只比较

开关中的内容

与

案例中的内容

您不应该这样使用开关

switch($var)
{
    case 1:
        //Some stuff
        break;
    case 2:
        //Some stuff
        break;
    default:
        break;
}

这是正确的做法。用ifs和ELSE去做，yadayda！你的虫子会消失

---

为什么?？因为

case

不是用来计算语句的。它只比较

开关中的内容

与

案例中的内容

您滥用了开关语句-如果

s，则应将其替换为
，或按如下方式更改：

switch ($result_lists)
{
     case 0:
         //To prove which option is actually happening 
         print_r('lists==0: '.$result_lists);  
         break;

     case 1:
         //To prove which option is actually happening 
         print_r('lists==1: '.$result_lists);  
         break;

     default:
         //To prove which option is actually happening 
         print_r('lists>1: '.$result_lists);
         break;
}

case($result_lists == 0):

// is like doing
if ($result_lists == ($result_lists == 0))

// which when $result_lists = 0 is the same as

if ($result_lists == true)
if (0 == 1)
// therefore false so it drops through to the next statement

case($result_lists > 1)
// the same as
if ($result_lists == ($result_lists > 1))
// when $result_lists = 0:
if ($result_lists == false)
if (0 == 0)

你现在做的是这样的：

switch ($result_lists)
{
     case 0:
         //To prove which option is actually happening 
         print_r('lists==0: '.$result_lists);  
         break;

     case 1:
         //To prove which option is actually happening 
         print_r('lists==1: '.$result_lists);  
         break;

     default:
         //To prove which option is actually happening 
         print_r('lists>1: '.$result_lists);
         break;
}

case($result_lists == 0):

// is like doing
if ($result_lists == ($result_lists == 0))

// which when $result_lists = 0 is the same as

if ($result_lists == true)
if (0 == 1)
// therefore false so it drops through to the next statement

case($result_lists > 1)
// the same as
if ($result_lists == ($result_lists > 1))
// when $result_lists = 0:
if ($result_lists == false)
if (0 == 0)

您正在滥用switch语句-应将其替换为
if
s，或按如下方式更改：

switch ($result_lists)
{
     case 0:
         //To prove which option is actually happening 
         print_r('lists==0: '.$result_lists);  
         break;

     case 1:
         //To prove which option is actually happening 
         print_r('lists==1: '.$result_lists);  
         break;

     default:
         //To prove which option is actually happening 
         print_r('lists>1: '.$result_lists);
         break;
}

case($result_lists == 0):

// is like doing
if ($result_lists == ($result_lists == 0))

// which when $result_lists = 0 is the same as

if ($result_lists == true)
if (0 == 1)
// therefore false so it drops through to the next statement

case($result_lists > 1)
// the same as
if ($result_lists == ($result_lists > 1))
// when $result_lists = 0:
if ($result_lists == false)
if (0 == 0)

你现在做的是这样的：

switch ($result_lists)
{
     case 0:
         //To prove which option is actually happening 
         print_r('lists==0: '.$result_lists);  
         break;

     case 1:
         //To prove which option is actually happening 
         print_r('lists==1: '.$result_lists);  
         break;

     default:
         //To prove which option is actually happening 
         print_r('lists>1: '.$result_lists);
         break;
}

case($result_lists == 0):

// is like doing
if ($result_lists == ($result_lists == 0))

// which when $result_lists = 0 is the same as

if ($result_lists == true)
if (0 == 1)
// therefore false so it drops through to the next statement

case($result_lists > 1)
// the same as
if ($result_lists == ($result_lists > 1))
// when $result_lists = 0:
if ($result_lists == false)
if (0 == 0)

请不要那么快验证答案，让人们回答。顺便说一句，这个答案可能有用，但它仍然是一个糟糕的答案。请不要那么快验证答案，让人们来回答。顺便说一句，这个答案可能有用，但它仍然是一个糟糕的答案。switch语句不是这样工作的。回答不好，对我来说是-1。switch语句不是这样工作的。回答不好，对我来说是-1。+1比我给出的解释多。如果可能的话，我会为机器人外观的代码行添加+1：
if（0==0）
：D+1以获得比我给出的更多的解释。如果可以的话，我会为机器人外观的代码行添加+1：
if（0==0）
：D