从一个MysqL的例子来学习查询语句
自上学这么多年以来,得出了从一个例子入手来学习是最快最有效,并能培养出很强的实践能力,这是一种很
好的学习方法。不访试试。比如看一本书的时候从各章节的例子入手,找出不了解的以及不懂的还是新知识,
进而有针对性的学习。看看下面的例子:
<?php $ip = getenv("REMOTE_ADDR"); //echo "$ip"; $conn = mysql_connect('ip', 'root', '****'); mysql_select_db('db', $conn); $sql = "select *from counter where ip="$ip";"; $result = mysql_query($sql, $conn); $num = mysql_num_rows($result); $count = mysql_query("select*from counter", $conn); $count = mysql_num_rows($count); //echo "$num"; //echo "$count"; if ($num == 0) { $sum = 1; $count; $sql = "insert into counter(ip,sum,countdata)values('$ip','1','$count')"; mysql_query($sql, $conn); mysql_close($conn); //echo "$count"; } else { $my = "select sum from counter where ip='$ip'"; $bbbbbb = mysql_query($my) or die(mysql_error()); $row = mysql_fetch_Array($bbbbbb); @$sum = $row[sum]; //echo "$sum"; $sum; $sql = "update counter set sum='$sum' where ip='$ip'"; mysql_query($sql); mysql_close($conn); } $str_count = strval($count); $str_count = Chop($str_count); $count_len = strlen($str_count); $image_count = ""; if ($count_len < 6) { for ($j = 0; $j < 6 - $count_len; $j) { $image_count = $image_count . "<img src='0.gif'>"; } } for ($i = 0; $i < $count_len; $i) { $nom = substr($str_count, $i, 1); $image_count = $image_count . "<img src='"; $image_count = $image_count . $nom; $image_count = $image_count . ".gif'>"; } echo "$image_count<br>"; print "这是你的第" . $sum . "次访问";
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