How to Use DataRow and display 0 in a text box if it is null or empty

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I am trying to read data from a table in my db. If that field in the table is
empty or null than it should display "0" in the textbox txtPreviousbalance.
Here is what I did but it is not working. What should I do?

SQL

SqlCommand cmd = new SqlCommand();
string sqlQuery2 = null;
sqlQuery2 = "select currentbalance from tblstudentfeesdetails where studentid='" + cboStudentid4.Text + "' order by dateofpayment desc";

cmd.Connection = conn;
cmd.CommandText = sqlQuery2;
cmd.CommandType = System.Data.CommandType.Text;

conn.Open();
SqlDataReader dr2 = null;
dr2 = cmd.ExecuteReader();

if (dr2.Read() == null)
{
	txtPreviousbalance.Text = "0";
}

if (conn.State != ConnectionState.Closed)
{
	conn.Close();
}

Posted 17-Jun-12 11:53am

mikeoabban

Updated 17-Jun-12 19:38pm

Prosan

v4

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3 solutions

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**R. Giskard Reventlov** · Answer 1 · 2012-06-17T12:17:00

There are a number of ways to tackle this. Here is one:

C#

if (string.IsNullOrEmpty(dr2.Read()))
{
	txtPreviousbalance.Text = "0";
}

Note that your code should actually read something like:

C#

while(dr2.Read())
{
   txtPreviousbalance.Text = string.IsNullOrEmpty(dr2.GetString(0)) ? "0" : dr2.GetString(0);
}

SqlCommand.ExecuteReader Method[^]

Again, change to suit.

Prosan · Answer 2 · 2012-06-17T19:26:00

Solution 2

in place of

C#

if (dr2.Read() == null)
{
    txtPreviousbalance.Text = "0";
}

u can uses different ways look:-

C#

if (dr2 == null)
{
    txtPreviousbalance.Text = "0";
}</

SQL

while (dr2.Read())
        {
txtPreviousbalance.Text =dr2["currentbalance"]==null ? "0" : dr2["currentbalance"].ToString()
}

Posted 17-Jun-12 19:26pm

Prosan

Updated 17-Jun-12 19:31pm

v2

Savalia Manoj M · Answer 3 · 2012-06-18T02:42:00

Solution 3

Hi,
You can also set "0" in Query like

sqlQuery2 = "select Case currentbalance When NULL 0 Else currentbalance End as currentbalance from tblstudentfeesdetails where studentid='" + cboStudentid4.Text + "' order by dateofpayment desc";

Posted 18-Jun-12 2:42am

Savalia Manoj M