PHP solves an infinite loop caused by compressed code_PHP tutorial

test.table1表

id	str1	str2
1	saa	bbb
2	saa	bbc
3	sss	123

Requirement: List the contents of the "str1" segment without duplication.

Originally it was very simple and only took a few lines, but I thought the code could be compressed a bit so that it looked more condensed, so something went wrong. The error code was as follows:

<?php
mysql_select_db("test", mysql_connect("localhost","******","******"));

while($row = mysql_fetch_array(mysql_query("SELECT DISTINCT str1 FROM table1")))
{
	echo $row['str1'];
	echo "<br>";
}
?>

Did you see the problem at first glance? This thing actually caused an endless loop. . . T_T

So I restored it step by step, and the infinite loop disappeared again. Obviously it is not a problem with the submission statement, but a problem with the grammatical structure.

Sure enough, the problem lies in while. Mysql_query will be executed every time a condition is detected. Then it was a mess.

Just make sure that mysql_query is executed only once. The correct code is as follows:

<?php
mysql_select_db("test", mysql_connect("localhost","******","******"));

$result = mysql_query("SELECT DISTINCT str1 FROM table1");
while($row = mysql_fetch_array($result))
{
	echo $row['str1'];
	echo "<br>";
}
?>

Optimizing code is the worst of all evils... Everyone, calm down, calm down!

http://www.bkjia.com/PHPjc/621611.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/621611.htmlTechArticletest.table1 table id str1 str2 1 saa bbb 2 saa bbc 3 sss 123 Requirement: No duplicate listing of "str1 "The content of the paragraph. It was originally very simple and only took a few lines, but I think the code can be compressed...