自选值插入数据库解决办法
自选值插入数据库
科目：有20个选项，自选5个。
班级：只能选一个。
然后自选的这个5个科目和班级会被写进数据库。就是要实现这么一个简单的功能，我虽然做出来了，但是觉得我做的不太合适。
我现在把科目和班级分成了两个表。相等于有两次insert，两次insert的id是AUTO_INCREMENT。所以理论上他们所对应的id也应该是能对上号的。但是显然这样很不合理。
其次，这样写的话实际上insert科目表的时候是把这20个都写进去了，只不过已选中的就把值写进去了，没选择的写进去的是空。然后在输出的都是也是把这20个全部输出，只不过有的是空所以最后只会看到有5个值输出，但是实际上却输出了20个，只不过另外15个是空罢了。
- PHP code
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<?php if(isset($_POST['submit'])){
$subjects_sql = "insert into subjects (`subjects_01`,`subjects_02`,`subjects_03`,`subjects_04`,`subjects_05`,`subjects_06`,`subjects_07`,`subjects_08`,`subjects_09`,`subjects_10`,`subjects_11`,`subjects_12`,`subjects_13`,`subjects_14`,`subjects_15`,`subjects_16`,`subjects_17`,`subjects_18`,`subjects_19`,`subjects_20`) values('$_POST[subjects_01]','$_POST[subjects_02]','$_POST[subjects_03]','$_POST[subjects_04]','$_POST[subjects_05]','$_POST[subjects_06]','$_POST[subjects_07]','$_POST[subjects_08]','$_POST[subjects_09]','$_POST[subjects_10]','$_POST[subjects_11]','$_POST[subjects_12]','$_POST[subjects_13]','$_POST[subjects_14]','$_POST[subjects_15]','$_POST[subjects_16]','$_POST[subjects_17]','$_POST[subjects_18]','$_POST[subjects_19]','$_POST[subjects_20]')";
$class_sql = "insert into class (`class_01`,`class_02`,`class_03`,`class_04`,`class_05`,`class_06`,`class_07`,`class_08`,`class_09`,`class_10`,`class_11`,`class_12`,`class_13`,`class_14`,`class_15`,`class_16`) values('$_POST[class_01]','$_POST[class_02]','$_POST[class_03]','$_POST[class_04]','$_POST[class_05]','$_POST[class_06]','$_POST[class_07]','$_POST[class_08]','$_POST[class_09]','$_POST[class_10]','$_POST[class_11]','$_POST[class_12]','$_POST[class_13]','$_POST[class_14]','$_POST[class_15]','$_POST[class_16]')";
if(mysql_query($subjects_sql) and mysql_query($class_sql)){
echo "<script>alert('提交成功');location.href='index.php';";
}else{
echo "<script>alert('提交失败');location.href='index.php';</script>";
}
}
?>
------解决方案--------------------
不太明白你的需求 要是我 我会这样子做 建一个科目表
选择的话是保存科目表的id 以字符串的形式 如 1,2,3 选择的班级也保存同一个表
显示选择科目时 select * from 科目表 where id in(1,2,3)
------解决方案--------------------
三个表：
科目表：
id
name
班级：
id
name
选修表：
id
科目ID (存科目id eg:1,2,3)
班级ID (存班级id)
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