如何学生老班和学生新班 [英] How can Facth Student Old Class And Student New Class

问题描述

学生表

----------------

Student table
----------------

StudentId       StudentCode       Student Name      Address        Class
   1                 001              kkp             noida        ClassI
   2                 002             kkpoi            Delhi        ClassII
   3                 003             kkpooi            mohali       ClassIV

Prometed Class Table

------------------------

Prometed Class Table
------------------------

PrometedId            NewClassId
    1                  ClassII
    2                  ClassIII

学生证书课程表

------------------------------

Student Prometed Class Table
------------------------------

StuPromid       PrometedId              StudentId
   1               1                       1
   2               1                       2
   3               2                       1

输出可以这个

---------------------

Output can this one
---------------------

StudentName           OldClass            NewClass
   kkp                  ClassI             ClassII
   kkpoi                ClassII            ClassIII
   kkpooi               ClassIV             Null

推荐答案

您需要加入3个表并获得所需的输出。例如

You need to join 3 tables and get the output you want. for example

SELECT a.au_lname, a.au_fname, t.title
FROM authors a INNER JOIN titleauthor ta
   ON a.au_id = ta.au_id JOIN titles t
   ON ta.title_id = t.title_id

明智的你可以加入多个表格，请阅读以下链接以获取更多信息

SQL联接 [ ^ ]

加入三个或更多表 [ ^ ]

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