如何使用ASP.NET从两个表中获取记录 [英] How to get records from two tables using ASP.NET

问题描述

朋友们，





i有一个问题..那就是我有两张桌子。



1.student 2。attendance



i想要两张桌子的结果..i表示谁在特定日期，团体和批次中缺席。 。



学生桌上有（身份，团体，批次）

考勤表有（身份证，日期）



i希望absentees数据按组和批次和日期排序..请告诉我如何为此编写查询..



我的尝试：

hi friends ,


i have a one problem..that is i have two tables .

1.student 2 .attendance

i want results from two tables ..i mean who's absent on particular date and group and batch..

student tables is haveing (id,group,batch)
attendance table having (id,date)

i want absentees data with sorting by group and batch and date..please tell me how to write a query for that..

What I have tried:

SELECT id,gender,vid,fname,mobino,fathername,date,batch,group,FROM tbl_studentenroll ee   WHERE not exists (SELECT vid,date FROM tbl_attendance aa where aa.vid=ee.vid and aa.date='" + ddl_date.SelectedItem.Text + "' and ee.group='" + ddl_group.SelectedItem.Text + "'  and ee.batch='" + ddl_batch.SelectedItem.Text + "' );

但它没有排序结果它显示所有组和批次缺席

but it is not sorting results it is shows all groups and batchs absents

推荐答案

SELECT id,gender,vid,fname,mobino,fathername,date,batch,group,FROM tbl_studentenroll ee   WHERE not exists (SELECT vid,date FROM tbl_attendance aa where aa.vid=ee.vid and aa.date='" + ddl_date.SelectedItem.Text + "' )
AND 
ee.group='" + ddl_group.SelectedItem.Text + "'  and ee.batch='" + ddl_batch.SelectedItem.Text + "' 
;

我已经更改了原始查询，如下所示：

in not exists子句，我通过删除ee.field引用来改变条件，因为你只从tlb_attendance <中选择br />
我将你的studentroll条件移到了存在检查之外。

I've changed your original query as follows:
in the not exists clause, I changed the condition by removing ee.field references since you're selecting only from tlb_attendance
I moved your studentroll conditions outside of existence check.

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