database coding....in c#

Question

4.00/5 (1 vote)

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i m new in this field. I have one problem.....
this is my coding.....

C#

con.Open();
 string str = "select name from tbl where city = 'xxx' ";
 cmd = new SqlCommand(str, con);
 dr = cmd.ExecuteReader();
 while (dr.Read())
 {
     Label lb = new Label();
     lb.Text = dr[0].ToString() + "<br>";
     form1.Controls.Add(lb);


     //-------- part 1 ------------------------------

     string val = "select * from othertbl where name= '" + dr[0].ToString(); +"'";
     cmd = new SqlCommand(val, con);
     dr = cmd.ExecuteReader();
     dr.Read();
     for(int a=0; a<10; a++)    //here 10 clm in database so i can take for loop
     {
     LinkButton lbn = new LinkButton();
     lbn.Text = dr[a].ToString() + "<br>";
     form1.Controls.Add(lbn);
     }
     //-----------------------------------------

 }
 con.Close();

when i run page without "part 1" whole portion... i get output like....

name1
name2
name3

but when i run this page with "part 1" that time i get output like.....

name1
lnk1
lnk2
lnk3

but i want to display like...

name1
lnk1
lnk2
lnk3

name2
lnk1
lnk2

name3
lnk1
lnk2
lnk3

here name and link is not fix which r dynamically changed according to data.
that type of coding possible for display data....? or any other idea like this...
plz help me... frnds

[edit]Code blocks added - OriginalGriff[/edit]

Posted 3-Sep-12 8:04am

jkpatelce

Updated 3-Sep-12 8:32am

OriginalGriff

v2

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3 solutions

Solution 2

You have reused the dr variable, thus you loose the outer DataReader on the first run of the loop. Change tho this:

C#

con.Open();
string str = "select name from tbl where city = 'xxx' ";
cmd = new SqlCommand(str, con);
dr1 = cmd.ExecuteReader();
while (dr1.Read())
{
    Label lb = new Label();
    lb.Text = dr[0].ToString() + "<br>";
    form1.Controls.Add(lb);


    //-------- part 1 ------------------------------

    string val = "select * from othertbl where name= '" + dr[0].ToString(); +"'";
    cmd = new SqlCommand(val, con);
    var dr2 = cmd.ExecuteReader();
    dr2.Read();
    for(int a=0; a<10; a++)    //here 10 clm in database so i can take for loop
    {
    LinkButton lbn = new LinkButton();
    lbn.Text = dr2[a].ToString() + "<br>";
    form1.Controls.Add(lbn);
    }
    //-----------------------------------------

}
con.Close();

Posted 3-Sep-12 8:40am

Zoltán Zörgő

Updated 3-Sep-12 8:41am

v2

Comments

jkpatelce 3-Sep-12 14:45pm

thnxx....... bro
i got it... thnk u so much

Zoltán Zörgő 3-Sep-12 16:20pm

Great! Than accept the solution, please.

member60 3-Sep-12 23:17pm

my 5!

Solution 3

Hi,

There are couple of mistakes in your code,

1) Your select statement for executing query is inside While loop. it's too bad practice. Instead you can use Join to generate your data with single query.
2) You should use StoredProcedure instead of hardcode query.
3) Why you have define 10 count in For loop ? Instead you can get that information from the database(from row count).
4) Closing connection should be in finally block or Connection should be enclosed with using.

Best luck
Thanks
-Amit Gajjar

Posted 3-Sep-12 15:56pm

AmitGajjar

Comments

jkpatelce 3-Sep-12 23:00pm

thnx.... amit
i am new in C#. so i have no full knlg about the all.
so now i can try to solve the problem according ur cmt.
if u have any best site or article for me... so give me a link.. plz

AmitGajjar 4-Sep-12 0:37am

OfCourse for beginner this all things are very new. but you need to search in MSDN for all this stuff.

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Philip Stuyck · Accepted Answer · 2012-09-03T08:37:00

Solution 1

You are making a terrible mistake using the same datareader.
by doing dr = cmd.executereader you are overwriting the one used in the loop.
You need two readers instances that operate independant from eachother.

Posted 3-Sep-12 8:37am

Philip Stuyck

Comments

[no name] 3-Sep-12 14:39pm

+5 correct ans

member60 3-Sep-12 23:17pm

my 5!