php?数据的读取
上课形式有很多种,不同的上课形式对应不同的科目,不同的科目对应不同的课程......
这些数据要怎么读取比较合适??
打算用的做法(
当用户点击下拉按钮时,通过ajax将上课形式的的值填充进去.
点击科目下拉按钮时,根据上课形式的选择,在通过ajax将科目的值填充进去
点一次,查一次
)
回复讨论(解决方案)
查表呗，每个上课形式都对应相应的科目
查表呗，每个上课形式都对应相应的科目
那些数据要一次性读出来,还是根据前一次选择,读取下一个??
你的 科目隶属于上课形式，课程隶属于科目
科目还没选定，你怎么取课程？
你的 科目隶属于上课形式，课程隶属于科目
科目还没选定，你怎么取课程？
你的 科目隶属于上课形式，课程隶属于科目
科目还没选定，你怎么取课程？
读取数据时把所有的上课形式和对应的科目一次性取出来,这个就不用一次又一次的访问数据库
都读出来，又用不上，不是浪费吗？
如果还要自己缓存起来，不嫌麻烦吗？
缓存到文件和直接访问数据库有什么区别呢？数据表也是文件
缓存到内存，要运行相关服务和加载相应扩展，不一样增加系统开销吗
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