如何连接两个表并使用2个下拉列表过滤结果 [英] how to join two tables and filter the result using 2 dropdownlists

问题描述

  string  str =  string  .Format（ @ 选择m.autoid，m.pcode，m.fyyear，m.date，m.salary，m.ta，m.contigency ，m.nrc，m.institcharges，m.others，y.yearlyalloc，y.salary，y.ta，y.contigency，y.nrc，y.institcharges，y.others FROM每月AS m内部加入年度y pcode where m.pcode =（' + DropDownList1.SelectedItem.ToString（）+  '）和y。 fyyear =（' + DropDownList2.SelectedItem.ToString（）+  '） ，con）; 
 SqlDataAdapter da =  new  SqlDataAdapter（str，con）; 
 DataTable dt =  new  DataTable（）; 
 da.Fill（dt）; 
 GridView1.DataSource = dt; 
 GridView1.DataBind（）; 
 

i能够过滤数据，但我无法做到的是如何将两个表连接在一起使用它们与dropdownlist条件

解决方案

查看INNER JOIN的语法

  SELECT  ft.col1，ft.col2，st.col1，st.col2 
  FROM  FristTable ft 
  INNER   JOIN  SecondTable st 
  ON  ft.colname = st.colname 

在您的查询中没有ON关键字...

更正内部联接查询使用on关键字连接两个表

示例：

 选择 *  FROM 每月 AS  m  inner  加入每年y   m.pcode = y.pcode 其中​​ m.pcode =（' + DropDownList1.SelectedItem.ToString（）+'） AND  y.fyyear =（' + DropDownList2.SelectedItem.ToString（）+  

string str = string.Format(@"select m.autoid,m.pcode, m.fyyear, m.date, m.salary, m.ta, m.contigency, m.nrc, m.institcharges, m.others,y.yearlyalloc,y.salary,y.ta,y.contigency,y.nrc,y.institcharges,y.others FROM monthly AS m inner join yearly y pcode where m.pcode=('" + DropDownList1.SelectedItem.ToString() + "' ) AND y.fyyear=('" + DropDownList2.SelectedItem.ToString() + "')", con);
       SqlDataAdapter da = new SqlDataAdapter(str, con);
       DataTable dt = new DataTable();
       da.Fill(dt);
       GridView1.DataSource = dt;
       GridView1.DataBind();

i am able to filter the data but i what i am not able to do is how to join two tables together and use them with dropdownlist condition

解决方案

see the syntax of INNER JOIN

SELECT ft.col1, ft.col2, st.col1, st.col2
FROM FristTable ft
INNER JOIN SecondTable st
ON ft.colname = st.colname

in your query there is no ON keyword...

correct the "inner join" query use "on" keyword to connect both tables
example:

select * FROM monthly AS m inner join yearly y on  m.pcode=y.pcode where m.pcode=('" + DropDownList1.SelectedItem.ToString() + "' ) AND y.fyyear=('" + DropDownList2.SelectedItem.ToString() + "'

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