Assuming that i have the database items:
Hello
Hello
Hello
I just want to display only one "Hello"
Here is my code....
OleDbCommand cmd = new OleDbCommand("Select *from login", con);
dr = cmd.ExecuteReader();
while (dr.Read())
{
combo1.Items.Add(dr["dtlogin"].ToString());
}
var value = dr["dtlogin"].ToString();
if (!combo1.Items.Contains(value))
{
combo1.Items.Add(value);
}
Check for the item before adding using Contains
if(!combo1.Items.Contains(dr["dtlogin"].ToString()))
{
combo1.Items.Add(dr["dtlogin"].ToString());
}
If you r looking for distinct value's to be bind to ur combobox then use this.
OleDbCommand cmd = new OleDbCommand("Select distinct * from login", con);
dr = cmd.ExecuteReader();
while (dr.Read())
{
combo1.Items.Add(dr["dtlogin"].ToString());
}
You can just use ExecuteScalar to get first column of the first row. Other rows are ignored.
I assume they are string, you can do;
using(OleDbCommand cmd = new OleDbCommand("Select dtlogin from login", con);)
{
string s = (string)cmd.ExecuteScalar();
combo1.Items.Add(s);
}
Also use using statement to dispose your OleDbCommand and con.
Related
I have code like that to fill that combo box fill my database
but cant .getString("NameCompany") error why ? the full code is here
private void FillCombobox()
{
cmd = new SqlCommand("Select * From Penawaran", con);
SqlDataReader dr;
string sName = dr.GetString("NameCustomer");
cbxNamaCustomer.Items.Add(sName);
}
First of all, you need to obtain your reader via the command, and assign it to the data reader. Once you've done so, iterate through each record. The connection you're passing through the SqlCommand constructor isn't defined anywhere. This will result in a NullReferenceException being thrown.
private void FillCombobox()
{
cmd = new SqlCommand("Select * From Penawaran", con);
SqlDataReader dr = cmd.ExecuteReader();
while(dr.read())
{
string sName = dr.GetString(0); // this should be the ordinal for the column you're trying to obtain.
cbxNamaCustomer.Items.Add(sName);
}
}
I'm trying to search my local database table and simply display all it's columns.
I start my sending in
SearchID("1234");
My code so far:
private static void SearchID(string CostumerID)
{
string conStr = #"Data Source = C:\Users\secwp_000\documents\visual studio 2012\Projects\Module5\Module5\Orderdatabase.sdf";
DataSet ds = new DataSet();
SqlCeConnection con = new SqlCeConnection(conStr);
SqlCeCommand cmd = new SqlCeCommand("SELECT * FROM [Order]", con);
SqlCeDataReader dr = cmd.ExecuteReader();
SqlCeDataAdapter adapt = new SqlCeDataAdapter(cmd);
adapt.Fill(ds, "Order");
while (dr.Read())
{
string str = (string)dr[1];
if (str == CostumerID)
{
Console.WriteLine(str);
}
}
}
Where am I thinking wrong?
It stops on
SqlCeDataReader dr = cmd.ExecuteReader();
saying i don't have a connection. But just sounds wierd, because I've just had connection..
You have to open connection using
If(con.state.toString()=="closed")
con.open();
I observe a fault in your query why are you compare your result after fetch from database.you can directly filter in SQL query
Select * from order where table.customer_Id = customerId
You have a connection but you haven't opened it yet:
con.Open();
adapt.Fill(ds, "Order");
con.Close();
In addition you should use using statements for disposable objects like SqlConnection and SqlCommand to make sure they will be disposed properly:
using(SqlCeConnection con = new SqlCeConnection(conStr))
using(SqlCeCommand cmd = new SqlCeCommand("SELECT * FROM [Order]", con))
{
}
I feel so stupid for not seeing this, haha. And it worked! But it wont display anything from the table,
while (dr.Read())
{
string str = (string)dr[1];
if (str == CostumerID)
{
Console.WriteLine(str);
}
}
Following instructions given to me, there is nothing wrong with this code, and it could display Order with costumerID 1234.
I'd really appreciate if someone could help me figure out how to fill two comboboxes data from two different tables. The code below doesn't seem to be working for me.
string command = "SELECT * FROM [Course]";
string command2 = "SELECT * FROM [Module]";
dbConnection db = new dbConnection();
SqlDataReader reader = db.commandExecute(command);
SqlDataReader reader2 = db.commandExecute(command2);
while (reader.Read())
{
comboBox2.Items.Add(reader["CourseID"].ToString());
}
while (reader2.Read())
{
comboBox1.Items.Add(reader["ModuleID"].ToString());
}
reader.Close();
reader2.Close();
db.connectionEnd();
Instead of using two queries you can try like this
string command = "SELECT * FROM [Course] UNION ALL SELECT * FROM [Module]";
If you have columns mismatch problem while joining query use NULL as Column1 for extra column
Eg-:
string command = "SELECT CUSTID AS ID FROM [Course] UNION ALL SELECT ModuleID AS ID FROM [Module]";
dbConnection db = new dbConnection();
SqlDataReader reader = db.commandExecute(command);
while (reader.Read())
{
comboBox2.Items.Add(reader["ID"].ToString());
}
reader.Close();
db.connectionEnd();
Update
I thought that you are going to add two table values in same comboxbox that's why posted above code.
Can you try this code it worked for me
SqlConnection con = new SqlConnection("Data Source=pcname;Initial Catalog=database;Persist Security Info=True;User ID=sa;Password=123");
SqlCommand cmd = new SqlCommand("SELECT * FROM [Course]", con);
SqlCommand cmd1 = new SqlCommand("SELECT * FROM [Module]", con);
con.Open();
SqlDataReader dr = cmd.ExecuteReader();
if (dr.HasRows)
{
while (dr.Read())
{
ComboBox1.Items.Add(dr(0).ToString);
}
}
dr.Close();
SqlDataReader dr1 = cmd1.ExecuteReader;
if (dr1.HasRows)
{
while (dr1.Read)
{
ComboBox2.Items.Add(dr1(0).ToString);
}
}
dr1.close();
con.close();
Hope this help you
Change your code
while (reader2.Read())
{
comboBox1.Items.Add(reader["ModuleID"].ToString());
}
with
while (reader2.Read())
{
// Change here the name of reader
comboBox1.Items.Add(reader2["ModuleID"].ToString());
}
I have the following:
String sql = "SELECT * FROM Temp WHERE Temp.collection = '" + Program.collection + "'";
SqlConnection conn = new SqlConnection(connString);
SqlCommand cmd = new SqlCommand(sql, conn);
Program.defaultCollection = (String)cmd.ExecuteScalar();
And I want to get the second column after executing the statement. I know it will return only one row with two columns
I have read online that I will have to read each row of the result, is there any other way?
ExecuteScalar gets the first column from the first row of the result set. If you need access to more than that you'll need to take a different approach. Like this:
DataTable dt = new DataTable();
SqlDataAdapater sda = new SqlDataAdapter(sql, conn);
sda.Fill(dt);
Program.defaultCollection = dt.Rows[0]["defaultCollection"];
Now, I realize that the field name may not be defaultCollection, but you can fill that in.
From the MSDN documentation for ExecuteScalar:
Executes the query, and returns the first column of the first row in the result set returned by the query. Additional columns or rows are ignored.
Now, as a final bit of advice, please wrap all ADO.NET objects in a using statement. Like this:
using (SqlConnection conn = new SqlConnection(connString))
using (SqlDataAdapter sda = new SqlDataAdapter(sql, conn))
{
DataTable dt = new DataTable();
sda.Fill(dt);
// do something with `dt`
}
this will ensure they are properly disposed.
And I want to get the second column after executing the statement
It is not possible with execute scalar.
is there any other way
You have 2 options here either to use SqlDataAdapter or SqlDataReader.
For you using DataReader is a recommended approach as you don't need offline data or do other worh
by using SqlDataAdapter
using (SqlConnection c = new SqlConnection(
youconnectionstring))
{
c.Open();
/
using (SqlDataAdapter a = new SqlDataAdapter(sql, c))
{
DataTable t = new DataTable();
a.Fill(t);
if(t.Rows.Count > 0)
{
string text = t.Rows[0]["yourColumn"].ToString();
}
}
}
by using DataREader
using (SqlConnection connection =
new SqlConnection(connectionString))
{
SqlCommand command =
new SqlCommand(sql, connection);
connection.Open();
SqlDataReader reader = command.ExecuteReader();
while (reader.Read())
{
//read data here
string text = reader.GetString(1)
}
reader.Close();
}
SqlCommand.ExecuteScalar() can be used only when the result have just one row and one column.
If you need more than one column to be returned, you should use something like this:
String sql = "SELECT * FROM Temp WHERE Temp.collection = '" + Program.collection + "'";
SqlConnection conn = new SqlConnection(connString);
using(SqlCommand cmd = new SqlCommand(sql, conn))
{
using(SqlDataReader rdr = cmd.ExecuteReader())
{
if(rdr.Read())
{
Program.defaultCollection = (String)rdr["Column1"];
Program.someOtherVar = (String)rdr["Column2"];
}
}
rdr.Close();
}
That will be the fastest way.
You can use a DataReader and read only the first column like:
IDataReader cReader = cmd.ExecuteReader();
if(cReader.Read())
{
string cText = cReader.GetString(1); // Second Column
}
ExecuteScalar only returns one value. You have to make sure your query only returns that value.
String sql = "SELECT temp.defaultCollection FROM Temp WHERE Temp.collection = '" + Program.collection + "'";
On a side note, read on SqlParameter. You don't want to concatenate values like that, you'll have a problem when the collection property contains a quote.
I want to populate data from a SQL Server database from many columns to many textboxes .. I have a code to populate just one box .. can someone edit my code... I want to pull data and show it in Name, Address, Telephone No and Date ... plz help .. this code works for only one textbox..
Thanks in advance
SqlConnection Conn = new SqlConnection(#"Data Source=rex;Initial Catalog=PersonalDetails;Integrated Security=True");
SqlCommand Comm1 = new SqlCommand("Select * From PersonalUsers ", Conn);
Conn.Open();
SqlDataReader DR1 = Comm1.ExecuteReader();
if (DR1.Read())
{
Name.Text = DR1.GetValue(0).ToString();
}
while (DR1.Read())
{
if(DR1.GetName() == "YourSQLColumnName")
{
YourTextBox.Text = (string) DR1["YourSQLColumnName"];
}
// Your Other textboxes and columns which you want to match should follow as this template
}
SqlCommand cmd = new System.Data.SqlClient.SqlCommand(sql, _conn);
SqlDataReader rdr = cmd.ExecuteReader();
System.Data.DataTable tbl = new System.Data.DataTable("Results");
tbl.Load(rdr);
if (tbl.Rows.Count > 0)
Name.Text = tbl.Rows[0]["column_name"].ToString();
string cs=System.Configuration.ConfigurationManager.ConnectionString["DBCS"].ConnectionString;
using(OracleConnection con=new OracleConnection(cs))
{
sql="select empname from Emp where empno='"+empno+"'";
OracleCommand cmd = new System.Data.OracleClient.OracleCommand(sql,con);
con.Open();
OracleDataReader rdr = cmd.ExecuteReader();
if(rdr.Read())
{
EmpName.Text=Convert.ToString(rd["empname"]);
}
}
I assume that you would like to take care of both more rows and more columns.
Try to specify the columns. It works without, but the performance is better if you do so.
I assume you have a class called PersonalUser with the specifed properties.
It is also nice to have it in an sorted order, so I added that
public List<PersonalUser> FetchMyData()
{
SqlConnection Conn = new SqlConnection(#"Data Source=rex;Initial Catalog=PersonalDetails;Integrated Security=True");
SqlCommand Comm1 = new SqlCommand("Select Name, Address, TelephoneNo,Date From PersonalUsers order by Name", Conn);
Conn.Open();
SqlDataReader DR1 = Comm1.ExecuteReader();
var result = new List<PersonalUser>();
while (DR1.Read())
{
result.Add(new PersonalUser {
Name = DR1.GetString(0);
Address= DR1.GetString(1);
TelephoneNo = DR1.GetString(2);
Date = DR1.GetString(3)
}
);
}
return result;
}
I would also, if the need is getting much complex than this, conidering using Entity Framwork..