通过不同的条件组装 一个sql语句
题目要求:目前需要通过不同会员信息的条件，对会员进行高级查询，这个时候就需要对sql语句的组装工作。需要查询的条件有，会员编号，会员昵称，会员帐号，会员注册时间，会员性别，条件通过GET方式传递给程序，通过任意选择这些条件进行查询，得到相应的结果。
参考：
会员表为user_bas 及其字段结构；
查询条件和数据库字段对应关系：
会员编号：id ；结构：smallint（6），查询为精确查询(比如:查询编号为1 2的会员)
会员昵称：nickname；结构：varchar(20) (比如:查询昵称里有”魅力”的昵称)
会员帐号：uname；结构：varchar(16) 查询为模糊查询
会员注册时间：regtime；结构：int(10) 查询为时间段查询
会员性别：sex；结构：tingint(1) 查询为 查询为精确查询
目标：
写一段程序，实现这样的查询功能,”查询条件”需要的时候会增加和减少,考生需要编写一套灵活的程序
注意：
1。灵活性，
用户可以选择1个条件，也可以一个都不选择，也可以选择多个。”
2。考虑到系统的性能
有的面试者用：
“select * from user_bas where id=’$id’ and nickname=’$nickname’ and sex=’$sex’…”
是不可以的，如果没有$id的条件数据库也还要去便历，在超过10万的数据库就非常慢了。
3。不用考虑接受数据问题，和传递给数据库如何解释的问题。
如果你怎么接受不知道如何书写，你可以更简单的思考，现在有几个变量。$id,$nickname,$uname,$sex,$regtime 可以用这些变量，但有的为空；对于数据库如何去查询，还有就是，数据库如何解释不用关心，如query相关函数语句你不用写。
4.不允许使用”where 1″或”where 1=1″类型的语法
代码
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<?php
if($_SERVER[‘REQUEST_METHOD‘]==’GET’){
$id=$_GET[‘id‘];
$nickname=$_GET[‘nickname‘];
$uname=$_GET[‘uname‘];
$regtime=$_GET[‘regtime‘];
$sex=$_GET[‘sex‘];
}
$ConditionsNumber=5;
$ConditionsArray=array(“$id “,”$nickname”,”$uname”,”$regtime”,”$sex”);
$SearchSQLArray=array(” where id =’$id’”,” where nickname = ‘$nickname’”,” where uname=’$uname’”,” where regtime=’$regtime’”,” where sex=’$sex’”);
for($i=0;$i<$ConditionsNumber;$i++)
{
if($ConditionsArray[$i]==”")
$SearchSQLArray[$i]=”";
$haveWhere=false;
for($j=0;$j<$i;$j++)
{
$wherePosition=strpos($SearchSQLArray[$j],”where”);
if(($wherePosition==”1″)&&($haveWhere==false))
{
$SearchSQLArray[$i]=ereg_replace(“where”,”and”,$SearchSQLArray[$i]);
$haveWhere=true;
} } }}
for($i=0;$i<$ConditionsNumber;$i++)
$sql=$sql.$SearchSQLArray[$i];
$query=”SELECT * FROM user_bas “.$sql.” order by id;”;
?>
3.目前有会员登陆的log记录数组，登陆日志里面有这个会员的编号（id）、会员帐号(uname)和登陆时间（logtime）。
通过这个数组需要得到如下统计：
（1）得到某一天中不同会员的登陆情况，一天内会员登陆了4次，就记4次。统计结果如：
在2006-07-20内的会员登陆情况
会员编号 会员帐号 会员登陆次数
1 User1 4次
3 User3 2次
2 User2 1次
（2）得到某几天内不同会员的登陆情况，会员在某一天登陆了很多次只记一次（也可以说会员在几天内有几天登陆了）。统计结果如：
在2006-07-20 到2006-07-22 的3天时间内的会员登陆情况：
会员编号 会员帐号 会员登陆次数
3 User3 3次
1 User1 2次
2 User2 2次
附件：
会员登陆日志数组：
$userlog[] = array (“id” => 2, “uname” => ‘user2′, “logtime” => ’2006-07-22 19:18:02′);
$userlog[] = array (“id” => 2, “uname” => ‘user2′, “logtime” => ’2006-07-22 18:15:03′);
$userlog[] = array (“id” => 2, “uname” => ‘user2′, “logtime” => ’2006-07-22 13:50:12′);
$userlog[] = array (“id” => 3, “uname” => ‘user3′, “logtime” => ’2006-07-22 13:12:09′);
$userlog[] = array (“id” => 3, “uname” => ‘user3′, “logtime” => ’2006-07-22 11:10:08′);
$userlog[] = array (“id” => 2, “uname” => ‘user2′, “logtime” => ’2006-07-22 10:52:54′);
$userlog[] = array (“id” => 3, “uname” => ‘user3′, “logtime” => ’2006-07-22 08:16:04′);
$userlog[] = array (“id” => 1, “uname” => ‘user1′, “logtime” => ’2006-07-21 19:18:02′);
$userlog[] = array (“id” => 1, “uname” => ‘user1′, “logtime” => ’2006-07-21 18:15:03′);
$userlog[] = array (“id” => 1, “uname” => ‘user1′, “logtime” => ’2006-07-21 13:50:12′);
$userlog[] = array (“id” => 3, “uname” => ‘user3′, “logtime” => ’2006-07-21 13:12:09′);
$userlog[] = array (“id” => 3, “uname” => ‘user3′, “logtime” => ’2006-07-21 11:10:08′);
$userlog[] = array (“id” => 1, “uname” => ‘user1′, “logtime” => ’2006-07-21 10:52:54′);
$userlog[] = array (“id” => 1, “uname” => ‘user1′, “logtime” => ’2006-07-21 08:16:04′);
$userlog[] = array (“id” => 1, “uname” => ‘user1′, “logtime” => ’2006-07-20 19:18:02′);
$userlog[] = array (“id” => 2, “uname” => ‘user2′, “logtime” => ’2006-07-20 18:15:03′);
$userlog[] = array (“id” => 1, “uname” => ‘user1′, “logtime” => ’2006-07-20 13:50:12′);
$userlog[] = array (“id” => 3, “uname” => ‘user3′, “logtime” => ’2006-07-20 13:12:09′);
$userlog[] = array (“id” => 3, “uname” => ‘user3′, “logtime” => ’2006-07-20 11:10:08′);
$userlog[] = array (“id” => 1, “uname” => ‘user1′, “logtime” => ’2006-07-20 10:52:54′);
$userlog[] = array (“id” => 1, “uname” => ‘user1′, “logtime” => ’2006-07-20 08:16:04′);
代码:
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<?php
$userlog[] = array (“id” => 2, “uname” => ‘user2′, “logtime” => ’2006-07-22 19:18:02′);
$userlog[] = array (“id” => 2, “uname” => ‘user2′, “logtime” => ’2006-07-22 18:15:03′);
$userlog[] = array (“id” => 2, “uname” => ‘user2′, “logtime” => ’2006-07-22 13:50:12′);
$userlog[] = array (“id” => 3, “uname” => ‘user3′, “logtime” => ’2006-07-22 13:12:09′);
$userlog[] = array (“id” => 3, “uname” => ‘user3′, “logtime” => ’2006-07-22 11:10:08′);
$userlog[] = array (“id” => 2, “uname” => ‘user2′, “logtime” => ’2006-07-22 10:52:54′);
$userlog[] = array (“id” => 3, “uname” => ‘user3′, “logtime” => ’2006-07-22 08:16:04′);
$userlog[] = array (“id” => 1, “uname” => ‘user1′, “logtime” => ’2006-07-21 19:18:02′);
$userlog[] = array (“id” => 1, “uname” => ‘user1′, “logtime” => ’2006-07-21 18:15:03′);
$userlog[] = array (“id” => 1, “uname” => ‘user1′, “logtime” => ’2006-07-21 13:50:12′);
$userlog[] = array (“id” => 3, “uname” => ‘user3′, “logtime” => ’2006-07-21 13:12:09′);
$userlog[] = array (“id” => 3, “uname” => ‘user3′, “logtime” => ’2006-07-21 11:10:08′);
$userlog[] = array (“id” => 1, “uname” => ‘user1′, “logtime” => ’2006-07-21 10:52:54′);
$userlog[] = array (“id” => 1, “uname” => ‘user1′, “logtime” => ’2006-07-21 08:16:04′);
$userlog[] = array (“id” => 1, “uname” => ‘user1′, “logtime” => ’2006-07-20 19:18:02′);
$userlog[] = array (“id” => 2, “uname” => ‘user2′, “logtime” => ’2006-07-20 18:15:03′);
$userlog[] = array (“id” => 1, “uname” => ‘user1′, “logtime” => ’2006-07-20 13:50:12′);
$userlog[] = array (“id” => 3, “uname” => ‘user3′, “logtime” => ’2006-07-20 13:12:09′);
$userlog[] = array (“id” => 3, “uname” => ‘user3′, “logtime” => ’2006-07-20 11:10:08′);
$userlog[] = array (“id” => 1, “uname” => ‘user1′, “logtime” => ’2006-07-20 10:52:54′);
$userlog[] = array (“id” => 1, “uname” => ‘user1′, “logtime” => ’2006-07-20 08:16:04′);
//第一题
$user=”;
$date=’2006-07-20′;
foreach($userlog as $val)
{
if(!isset($user[$val[‘id‘]]))
{
$user[$val[‘id‘]][‘id‘]=$val[‘id‘];
$user[$val[‘id‘]][‘uname‘]=$val[‘uname‘];
$user[$val[‘id‘]][‘logcounts‘]=0;
}
if(strstr($val[‘logtime‘],$date))
{
$user[$val[‘id‘]][‘logcounts‘]+=1;
}
}
echo ‘’;
print_r($user);
echo ‘’;
//第二题
$users=”;
$start=strtotime(’2006-07-20′);
$end =strtotime(’2006-07-22′)+3600*24;
$time=”;
foreach($userlog as $val)
{
if(!isset($users[$val[‘id‘]]))
{
$users[$val[‘id‘]][‘id‘]=$val[‘id‘];
$users[$val[‘id‘]][‘uname‘]=$val[‘uname‘];
$users[$val[‘id‘]][‘days‘]=array();
$users[$val[‘id‘]][‘logs‘]=0;
}
$time=strtotime($val[‘logtime‘]);
if($time>=$start & $time<$end)
{
if(!in_array(substr($val[‘logtime‘],0,10),$users[$val[‘id‘]][‘days‘]))
{
$users[$val[‘id‘]][‘days‘][]=substr($val[‘logtime‘],0,10);
$users[$val[‘id‘]][‘logs‘]+=1;
}
}
}
echo ‘’;
print_r($users);
echo ‘’;
?>
来源http://www.jobui.com/mianshiti/it/php/4225/