given value exist in database or not in ASP.NET

Write code after fill dataset

string tag_no = convert.tostring(ds.tables[0].row[0]["TagId"]);

if(tag_id==tag_no)
{
return true;
}
else
{
return false;
}

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Let me know please.

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public bool Data()
{
String Tno=102.1.01;
string Con = System.Configuration.ConfigurationManager.ConnectionStrings["stgdbConnectionString"].ConnectionString;
SqlConnection con1 = new SqlConnection(Con);

//SqlDataAdapter da = new SqlDataAdapter("SELECT [TagId],[BatchId],[ClientId] FROM TagTable", con1);
SqlDataAdapter da=new SqlDataAdapter("select [TagId] from TagTable where TagId="+Tno,con1);

DataSet ds = new DataSet();

da.Fill(ds, "TagTable");
string tag_no = ds.Tables[0].Rows[0]["TagId"].ToString();

if (Tno == tag_no)
{
return true;
}
else
{
return false;
}
}
I am writting this code getting an error like this
Incorrect syntax near '.01'.

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public bool Data()
{
String Tno="102.1.01";//String value!!!
string Con = System.Configuration.ConfigurationManager.ConnectionStrings["stgdbConnectionString"].ConnectionString;
SqlConnection con1 = new SqlConnection(Con);

//SqlDataAdapter da = new SqlDataAdapter("SELECT [TagId],[BatchId],[ClientId] FROM TagTable", con1);
SqlDataAdapter da=new SqlDataAdapter("select [TagId] from TagTable where TagId="+Tno,con1);

DataSet ds = new DataSet();

da.Fill(ds, "TagTable");
string tag_no = ds.Tables[0].Rows[0]["TagId"].ToString();

if (Tno == tag_no)
{
return true;
}
else
{
return false;
}
}

http://hashtagakash.wordpress.com/

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change this in sqldataadapter,:-

select [TagId] from TagTable where TagId = '"+ TagId +"'

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In this case, better to user ExecuteScalar() method of the SqlCommand objcet and also Parameterized statement. ExecuteScalar() gives the first column of first row data, in this case you will get the value of TagId as object if exists otherwise you get null.

Have a look at this example - http://www.dotnetfunda.com/codes/show/965/how-to-check-whether-a-username-exists-in-our-database-or-not.

Thanks

Regards,
Sheo Narayan
http://www.dotnetfunda.com

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hi..
I have managed to do the following...

string connectionString = "datasource=localhost;username=xxx;password=xxx;database=xxx";
MySqlConnection mySqlConnection = new MySqlConnection(connectionString);

string selectString =
"SELECT username, password " +
"FROM forum_members " +
"WHERE username = '" + frmUsername.Text + "' AND password = '" + frmPassword.Text + "'";

MySqlCommand mySqlCommand = new MySqlCommand(selectString, mySqlConnection);
mySqlConnection.Open();
String strResult = String.Empty;
strResult = (String)mySqlCommand.ExecuteScalar();
mySqlConnection.Close();

if (strResult.Length == 0)
{
Label1.Text = "INCORRECT USER/PASS!"
//could redirect to register page
} else {
Label1.Text = "YOU ARE LOGGED IN!";
//set loggin in sessions variables
}

SAMIR
Sr. Software Engineer

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