make adapter gets multiple statement

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1.00/5 (1 vote)

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C#

SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["connection"].ConnectionString);
SqlCommand com = new SqlCommand();
con.Open();
com.Connection = con;

//get course id's for this teacher
string cmd1 = "select course_id from course_teacher where teacher_id='" + Session["t_id"] + "'";
SqlDataAdapter da1 = new SqlDataAdapter(cmd1, con);
DataSet ds1 = new DataSet();
da1.Fill(ds1);
string cmd2 = "";
for (int i = 0; i < ds1.Tables[0].Rows.Count; i++)
{
int courseid = Convert.ToInt32(ds1.Tables[0].Rows[i]["course_id"].ToString());
cmd2 += "select (course_name+'-'+class_name)from courses where course_id='" + courseid + "'";
}
SqlDataAdapter da2 = new SqlDataAdapter(cmd2, con);
DataSet ds2 = new DataSet();
da2.Fill(ds2);
DropDownList1.DataSource = ds2;
DropDownList1.DataBind();

the problem is the adapter in the loop gets just the first statement...

Posted 15-Apr-13 6:19am

amr mustafa

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[no name] 15-Apr-13 12:30pm

Probably because,
1. you are concatenating select (course_name+'-'+class_name)from courses where course_id='" + courseid + "'" over and over which is going to turn out to be an invalid SQL statement
and 2 courseid is an integer and presumably an int in your database also but you are treating as if it were a string in your SQL statement.

2 solutions

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José Amílcar Casimiro · Answer 1 · 2013-04-15T06:27:00

Solution 1

Hi,

This code block:

SqlDataAdapter da2 = new SqlDataAdapter(cmd2, con);
DataSet ds2 = new DataSet();
da2.Fill(ds2);
DropDownList1.DataSource = ds2;
DropDownList1.DataBind();

is outside for loop statement and that is the reason why you can't get results from the second adapter.

Cheers,
JAFC

Posted 15-Apr-13 6:27am

José Amílcar Casimiro

Comments

amr mustafa 15-Apr-13 12:32pm

i tried this but i want to do it without decrease the performance while get the data from the Database

José Amílcar Casimiro 15-Apr-13 12:46pm

What do you mean by decrease the performance? Have the UI locked? If so, make an async thread to get the data.

Raj Parashar · Answer 2 · 2013-04-15T07:23:00

all of the above you want to have the data in a dataset or datatable right. so pls do the following which should solve your problem

//get course ids for this teacher
string cmd1 = "select course_id from course_teacher where teacher_id='" + Session["t_id"] + "'";
SqlDataAdapter da1 = new SqlDataAdapter(cmd1, con);
DataSet ds1 = new DataSet();
da1.Fill(ds1);
string cmd2 = "";
Datatable dt-new DataTable();
for (int i = 0; i < ds1.Tables[0].Rows.Count; i++)
{
int courseid = Convert.ToInt32(ds1.Tables[0].Rows[i]["course_id"].ToString());
cmd2 = "select (course_name+'-'+class_name)from courses where course_id='" + courseid + "'";
SqlDataAdapter da2 = new SqlDataAdapter(cmd2, con);
DataSet ds2 = new DataSet();
da2.Fill(ds2);

if(i=0)
{
dt=ds2.tables[0];
}
else
{
dt.merge(ds2.tables[0]);
}
}

DropDownList1.DataSource = dt;
DropDownList1.DataBind();

and i am sure it will solve your problem.....