What is the difference between the two ways of writing PHP? Solution Ideas

What is the difference between the two ways of writing PHP?
First wording:

$sql = "SELECT * FROM table";

$query =mysql_query ($sql);

while ($row =mysql_fetch_array ($query);) {

echo "Output";

}







The second wording:
$sql = "SELECT * FROM table";

$query =mysql_query ($sql);

$row =mysql_fetch_array ($query);

while ($row) {

echo "Output";

}

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while ($row =mysql_fetch_array ($query)), see if the value of the $row=mysql_fetch_array ($query) expression is true, if yes, the loop part is executed, and then go back to the previous check $row=mysql The value of _fetch_array ($query) is so looped.
In the second example, $row its value no longer changes, that is, the loop body is never executed, or it is executed forever.
You may need to understand the role of the next Mysql_fetch_array ().
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Upstairs positive solution. In addition to Mysql_fetch_array (), this method can also call the Mysql_fetch_object () method to get the results of the SQL query. The specific usage is not to repeat. Baidu a bit above a lot
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PHP code

while ($row =mysql_fetch_array ($query)) {//mysql_ Fetch_array A pointer to the internal resource, each call to the downstream data.//Because it is the inlet condition cycle, and then the formation of $row in each judgment is the downlink data, thus can determine whether to reach the end of the data//The second 2 floor said almost. 
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 2 Floor positive solution, the Mosaic 
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 The difference is: The former is correct, the latter is wrong 
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 The first is traversal, and the second is to take the first row, so simple 
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 The first one looks like a syntax error (a semicolon in the while expression); the second notation of 
 
 looks like a dead loop. 
 
 
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 The result of the second kind of loop ... It seems that I have had the experience of the cycle of death. The only way to reboot: 
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