从数据库中选择数据并将其显示到gridview [英] selecting data from database and showingg it to gridview

问题描述

{
OleDbConnection cn = new OleDbConnection();
        cn.ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0; Data Source=E:\placement cell\project.mdb";
        cn.Open();
        string sql1 = "select name from student where 10thper>=''" + DropDownList3.Text + "''AND  12thper>=''" + DropDownList4 + "''AND aggregate>=''" + DropDownList5 + "''AND backlog<=''" + DropDownList6 + "''AND academicgap<=''" + DropDownList7 + "''";
        System.Data.OleDb.OleDbCommand cmd1 = new System.Data.OleDb.OleDbCommand(sql1, cn);
        System.Data.OleDb.OleDbDataAdapter adp = new OleDbDataAdapter();
        DataSet ds = new DataSet();
        adp.SelectCommand = cmd1;
        adp.Fill(ds);
        DataTable dt = ds.Tables[0];
        OleDbDataReader dr = cmd1.ExecuteReader();
        while (dr.Read() == true)
        {
            GridView1.DataSource = dt;
        }
        cn.Close();
        }

这是代码.
错误是

this is the code.
the error is

Server Error in ''/placement cell'' Application.<br />
Syntax error (missing operator) in query expression ''10thper>=''55''AND  12thper>=''System.Web.UI.WebControls.DropDownList''AND aggregate>=''System.Web.UI.WebControls.DropDownList''AND backlog<=''System.Web.UI.WebControls.DropDownList''AND academicgap<=''System.Web.UI.WebControls.DropDownList''''.<br />
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.<br />
<br />
Exception Details: System.Data.OleDb.OleDbException: Syntax error (missing operator) in query expression ''10thper>=''55''AND  12thper>=''System.Web.UI.WebControls.DropDownList''AND aggregate>=''System.Web.UI.WebControls.DropDownList''AND backlog<=''System.Web.UI.WebControls.DropDownList''AND academicgap<=''System.Web.UI.WebControls.DropDownList''''.<br />
<br />
Source Error:<br />
<br />
Line 146:        DataSet ds = new DataSet();<br />
Line 147:        adp.SelectCommand = cmd1;<br />
Line 148:        adp.Fill(ds);<br />
Line 149:        DataTable dt = ds.Tables[0];<br />
Line 150:        OleDbDataReader dr = cmd1.ExecuteReader();<br />
<br />
Source File: e:\placement cell\recsearch.aspx.cs    Line: 148

推荐答案

给个 space before all AND operator.

string sql1 = "select name from student where 10thper>=''" + DropDownList3.Text + "'' AND  12thper>=''" + DropDownList4 + "'' AND aggregate>=''" + DropDownList5 + "'' AND backlog<=''" + DropDownList6 + "'' AND academicgap<=''" + DropDownList7 + "''";

您需要在''和AND之间留一个空格("''AND aggregate>"应为"'' AND aggregate")

请注意，在查询中，您正在直接与下拉列表进行比较，例如2thper> =''System.Web.UI.WebControls.DropDownList''对我来说似乎是错误的.您应该将内容内部下拉列表进行比较.

You need to give a space between '' and AND ("''AND aggregate>" should be "'' AND aggregate")

A note, in your query, you are doing comparisons directly to the dropdownlist e.g. 2thper>=''System.Web.UI.WebControls.DropDownList'' which to me appears to be wrong. You should compare to the content inside the drop down list.

主要是语法错误.请按以下方式重写查询，

Hi,
Mostly syntax error.Please rewrite the query as follows,

{
 OleDbConnection cn = new OleDbConnection();
 cn.ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0; Data Source=E:\placement cell\project.mdb";
 cn.Open();
 string sql1 = "select name from student where 10thper>=''" + DropDownList3.SelectedValue + "'' AND  12thper>=''" + DropDownList4.SelectedValue + "'' AND aggregate>=''" + DropDownList5.SelectedValue + "''AND  backlog<=''" + DropDownList6.SelectedValue + "'' AND academicgap<=''" + DropDownList7.SelectedValue + "''";
 System.Data.OleDb.OleDbCommand cmd1 = new System.Data.OleDb.OleDbCommand(sql1, cn);
 System.Data.OleDb.OleDbDataAdapter adp = new OleDbDataAdapter();
 DataSet ds = new DataSet();
 adp.SelectCommand = cmd1;
 adp.Fill(ds);
 DataTable dt = ds.Tables[0];
 OleDbDataReader dr = cmd1.ExecuteReader();
 while (dr.Read() == true)
 {
  GridView1.DataSource = dt;
 }
 cn.Close();
}

希望这会有所帮助.

Hope this will help.

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