blocks|key|338699|text|首先，每个循环都将获取mysql数据。因为内部条件检查语句将运行每个检查。第二个只运行一次。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|338700|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

First one will fetching mysql data every loop. Because statement inside condition checking will run each checking. Second one is only run once.

blocks|key|1633597|text|第二个while语句在while(condition){}中没有任何条件，现在您刚刚声明了一个变量。因此，它不会以与第一个语句相同的方式执行。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1633598|entityMap^0|B|I|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

the second while statement has no condition inside <code>while(condition){}</code> right now you have just declared a variable. hence it does not execute in the same manner as the first statement.

blocks|key|336431|text|//First+ex
while+($rows+=+mysqli_fetch_assoc($query))+{
print_r($rows);
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|336432|这是在每次迭代时执行的，因此在每次迭代时将下一个值放入$row中。|unstyled|offset|length|style|CODE|336433|//second+ex
$rows+=+mysqli_fetch_assoc($query);
while+($rows)+{
print_r($rows);
}|336434|在上面的代码中，您只将第一个迭代值放入$row。$row不会在每次迭代中得到更新。所以这将永远持续下去。|336435|结论:|BOLD|336436|每次调用mysqli_fetch_assoc($query)时，它都会给出下一行。|blockquote|336437|在第一个示例中，$row通过在每次迭代中一次又一次地调用mysqli_fetch_assoc($query)，在每次迭代中都有下一行。|336438|而在第二个示例中，mysqli_fetch_assoc($query)只被调用一次。因此，您的$row在每次运行时都有价值，而它将运行无限时间。|336439|entityMap^0|0|R|4|0|0|J|4|O|4|0|0|3|0|4|Q|0|S|Q|0|9|Q|1B|4|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|11|8|@$G|12|H|13|I|J]]|9|@]|A|$]]|$1|K|3|L|5|6|7|14|8|@]|9|@]|A|$B|C]]|$1|M|3|N|5|F|7|15|8|@$G|16|H|17|I|J]|$G|18|H|19|I|J]]|9|@]|A|$]]|$1|O|3|P|5|F|7|1A|8|@$G|1B|H|1C|I|Q]]|9|@]|A|$]]|$1|R|3|S|5|T|7|1D|8|@$G|1E|H|1F|I|J]]|9|@]|A|$]]|$1|U|3|V|5|F|7|1G|8|@$G|1H|H|1I|I|J]]|9|@]|A|$]]|$1|W|3|X|5|F|7|1J|8|@$G|1K|H|1L|I|J]|$G|1M|H|1N|I|J]]|9|@]|A|$]]|$1|Y|3|-4|5|F|7|1O|8|@]|9|@]|A|$]]]|Z|$]]

<pre><code>//First ex
while ($rows = mysqli_fetch_assoc($query)) {
print_r($rows);
}
</code></pre>

This is getting executed at each iteration so putting next value inside <code>$row</code> at each iteration. 

<pre><code>//second ex
$rows = mysqli_fetch_assoc($query);
while ($rows) {
print_r($rows);
}
</code></pre>

In above code you are putting only first iteration value to <code>$row</code>. <code>$row</code> is not getting updated at each iteration. So this will run forever.

Conclusion : 

<blockquote>
 Each time you call <code>mysqli_fetch_assoc($query)</code> it gives next row.
</blockquote>

In first example, $row is having next row at each iteration by calling <code>mysqli_fetch_assoc($query)</code> again and again on every iteration.

Whereas in second example <code>mysqli_fetch_assoc($query)</code> is getting called only once. So your <code>$row</code> will have value every time you run while so it will run for infinite time.

blocks|key|3047212|text|//mysql+users+table
//id+%7C+nick+%7C+date
//1++++%7C+x1++++%7C+2018-01-05
//2++++%7C+x2++++%7C+2018-01-06
//3++++%7C+x3++++%7C+2018-01-07

while+($row+=+mysqli_fetch_assoc($query))+{
++++print_r($row);
}

//first+loop+call+row+one
//second+loop++call+row+two
//third+loop++call+row++three

print_r(mysqli_fetch_assoc($query));+//print+row+one+and+mysql+cursor+jump+to+row+two
print_r(mysqli_fetch_assoc($query));+//print+row+two+and+mysql+cursor+jump+to+row+there
print_r(mysqli_fetch_assoc($query));+//print+row+there

//but+mysqli_fetch_assoc+bring+one+row+not+rows
$row+=+mysqli_fetch_assoc($query);


//row+is+null,+no+print+and+repeat
//row+is+null,+no+print+and+repeat
//row+is+null,+no+print+and+repeat
//row+is+null,+no+print+and+repeat
//+∞+:))
while+($row)+{
++++print_r($row);
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|3047213|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>//mysql users table
//id | nick | date
//1 | x1 | 2018-01-05
//2 | x2 | 2018-01-06
//3 | x3 | 2018-01-07

while ($row = mysqli_fetch_assoc($query)) {
 print_r($row);
}

//first loop call row one
//second loop call row two
//third loop call row three

print_r(mysqli_fetch_assoc($query)); //print row one and mysql cursor jump to row two
print_r(mysqli_fetch_assoc($query)); //print row two and mysql cursor jump to row there
print_r(mysqli_fetch_assoc($query)); //print row there

//but mysqli_fetch_assoc bring one row not rows
$row = mysqli_fetch_assoc($query);


//row is null, no print and repeat
//row is null, no print and repeat
//row is null, no print and repeat
//row is null, no print and repeat
// ∞ :))
while ($row) {
 print_r($row);
}
</code></pre>

Why does not the second example work the same way as the first? 
Look at the condition of the loop. Is it not exactly the same condition just different ways of writing it?

The first example becomes false when there is nothing more to get. And then it stops.
But the second example never becomes false, it keeps filling the screen with results and never gets done. Endless loop. 

Why does the examples behave differently and not exactly the same?

<pre><code>//First ex
while ($rows = mysqli_fetch_assoc($query)) {
print_r($rows);
}



//second ex
$rows = mysqli_fetch_assoc($query);
while ($rows) {
print_r($rows);
}
</code></pre>

While loop condition php

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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为什么第二个例子不像第一个例子那样工作呢？看看循环的情况。它不是完全相同的条件，只是不同的方式写它？当没有更多的东西可得到时，第一个例子就变成了假的。然后它就停止了。但是第二个例子永远不会变成错误，它总是用结果填充屏幕，永远不会完成。无止境的循环。为什么这些例子表现得不同而不完全相同呢？//First exwhile ...

问同时循环条件php
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