I'm passing a query and parameter from a WinForm to a database class. The
The code on the Form looks like this:
string selectedComp = "CPSI";
string catsQuery = "SELECT id, category, old_value, old_desc, new_value, new_desc, reference1, reference2 FROM masterfiles.xref WHERE company_name = '#company' ORDER BY category, old_value";
Db categoriesData = new Db();
dgvCategories.DataSource = categoriesData.GetData(catsQuery, selectedComp);
And in my database class my code to populate the datatable/set is this:
public DataTable GetData(string selectQuery, string selectedComp)
{
NpgsqlConnection conn = new NpgsqlConnection(connString);
DataSet ds = new DataSet();
NpgsqlCommand cmd = new NpgsqlCommand(selectQuery, conn);
cmd.Parameters.Add(new NpgsqlParameter("#company", selectedComp));
//cmd.Parameters.AddWithValue("#company", selectedComp);
//cmd.Parameters.Add("#company", NpgsqlDbType.Text);
//cmd.Parameters["#company"].Value = selectedComp;
try
{
conn.Open();
NpgsqlDataAdapter da = new NpgsqlDataAdapter(selectQuery, conn);
conn.Close();
da.Fill(ds);
return ds.Tables[0];
}
}
But putting a breakpoint at NpgsqlDataAdapter da = new NpgsqlDataAdapter(selectQuery, conn);, selecctQuery hasn't changed - the '#company' is still in the query.
What am I missing?
The root problem is that you're passing the query to the data adapter instead of the command. Change
NpgsqlDataAdapter da = new NpgsqlDataAdapter(selectQuery, conn);
to
NpgsqlDataAdapter da = new NpgsqlDataAdapter(cmd);
I would also use using to dispose of all objects, and don't close the connection until the dataset is filled:
using(NpgsqlConnection conn = new NpgsqlConnection(connString))
using(NpgsqlCommand cmd = new NpgsqlCommand(selectQuery, conn))
{
cmd.Parameters.Add(new NpgsqlParameter("company", selectedComp));
conn.Open();
using(NpgsqlDataAdapter da = new NpgsqlDataAdapter(cmd))
{
DataSet ds = new DataSet();
da.Fill(ds);
}
conn.Close();
return ds.Tables[0];
}
Related
I have created a form in asp.net,where i have some textbox, in which I have taken some input which is stored in the database. I have created another page where I have taken the same number of label as the textbox.
I want to show the data in the labels that I last entered.
How can i do that?
Code:
string cs = ConfigurationManager.ConnectionStrings["TrishanConnection"].ConnectionString;
SqlConnection con = new SqlConnection(cs);
SqlDataAdapter da = new SqlDataAdapter("SELECT TOP 1 coil_id FROM CoilDetails ORDER BY coil_id DESC", con);
con.Open();
DataSet ds = new DataSet();
da.Fill(ds);
LabeCoilid.Text = ds.ToString();
LabeCoilid.DataBind();
con.Close();
Try instead of
LabeCoilid.Text = ds.ToString();
this
LabeCoilid.Text = ds.Tables[0].Rows[0][0].ToString();
LabeCoilid.Text = ds.Tables[0].Rows[0]["coil_id"].ToString();
You don't need to call DataBind()
string cs = ConfigurationManager.ConnectionStrings["TrishanConnection"].ConnectionString;
using(SqlConnection con = new SqlConnection(cs))
{
using (SqlDataAdapter da = new SqlDataAdapter("SELECT TOP 1 coil_id FROM CoilDetails ORDER BY coil_id DESC", con))
{
con.Open();
DataSet ds = new DataSet();
DataTable dt = new DataTable();
da.Fill(ds);
dt=ds.Table[0]
}
}
LabeCoilid.Text = dt.Rows[0][0].ToString();
LabeCoilid.DataBind();
con.Close();
You can change the rows and columns by changing dt,Rows[4][8]
I have this access db that I have a ddl for the state name and a ddl for the year. I have a gridview that I'd like to pass the value of the state drop down list into where clause. Obviously if I could use sql with the named parameters I would but this is what I'm stuck with and not sure exactly how to format it correctly.
the drop down list is name ddlStates. In the parameters I've tried
mycommand.Parameters.Add("#ddlStates")
here is the data set
public DataSet GetData()
{
DataSet ds;
using (OleDbConnection myConnString = new OleDbConnection())
{
myConnString.ConnectionString = connString;
using (OleDbCommand myCommand = new OleDbCommand())
{
myCommand.CommandText = "select * from tblTest where location = ?";
myCommand.Parameters.Add();
myCommand.Connection = myConnString;
using (OleDbDataAdapter da = new OleDbDataAdapter())
{
da.SelectCommand = myCommand;
ds = new DataSet();
da.Fill(ds, "Grades");
}
}
return ds;
}
}//ends get data dataset
1.you need to open your connection
2.you can add the parameter as follows
public DataSet GetData()
{
DataSet ds;
using (OleDbConnection conn = new OleDbConnection(connString))
{
string query= "select * from tblTest where location = ?";
using (OleDbCommand myCommand = new OleDbCommand(query, conn))
{
myCommand.Parameters.AddWithValue("#ddlStates", <your value>);
conn.Open();
using (OleDbDataAdapter da = new OleDbDataAdapter(myCommand, conn))
{
ds = new DataSet();
da.Fill(ds, "Grades");
return ds;
}
}
}
}
myCommand.Parameters.AddWithKey("location", this.ddlStates.SelectedValue);
That assumes that the data type of the location column is textual. If it's numeric or something else then convert the SelectedValue to the appropriate data type first.
How can i get the value of company_name from Comp table and store it on a comboBox?
here is my initial code on getting the values from Database and store it on a combobox:
string Sql = "select company_name from JO.dbo.Comp";
SqlConnection conn = new SqlConnection(connString);
SqlCommand cmd = new SqlCommand(Sql, conn);
cmd.CommandType = CommandType.StoredProcedure;
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
da.Fill(ds);
for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
comboBox1.Items.Add(ds.Tables[0].Rows[i][0].ToString());
it point out to da.fill(ds) and says "Could not locate entry in sysdatabases for database 'select company_name from JO'. No entry found with that name. Make sure that the name is entered correctly."
hope for your reply thanks!
Use datareader it is much simpler \
string Sql = "select company_name from JO.dbo.Comp";
SqlConnection conn = new SqlConnection(connString);
conn.Open();
SqlCommand cmd = new SqlCommand(Sql, conn);
SqlDataReader DR = cmd.ExecuteReader();
while (DR.Read())
{
combobox1.Items.Add(DR[0]);
}
If you set up your connection string to be something of this sort:
string SqlConnectionString = "Data Source=[SERVER];Initial Catalog=[DATABASE];"
Then using that set up, you can set your string 'Sql' as:
string Sql = "select company_name from dbo.Comp";
This could be a possible set up you could use to read out the values.
using (SqlConnection saConn = new SqlConnection(this.ConnectionString))
{
saConn.Open();
string query = "select DBName from dbo.Company";
SqlCommand cmd = new SqlCommand(query, saConn);
using (SqlDataReader saReader = cmd.ExecuteReader())
{
while (saReader.Read())
{
string name = saReader.GetString(0);
combobox1.Add(name);
}
}
saConn.Close();
}
I would like to introduce you a very simple way to SQL data into a combobox as:
first you have a create a SQL table,
in C# platform drop a combobox and go to its property,
in the property menu click on "DataSource"
specify the database and table to load into combobox,
Note, the combobox name and table's row should be the same.
{
SqlConnection con =new SqlConnection("Data Source=Server_Name;Initial Catalog=Database_Name;integrated security=true");
SqlCommand cmd;
SqlDataReader dr;
private void CashMemoForm_Load(object sender, EventArgs e)
{
con.Open();
cmd = new SqlCommand("Select Column_Name From Table_Name", con);
dr = cmd.ExecuteReader();
while (dr.Read())
{
comboBox1.Items.Add(dr[0]).ToString();
}
}
}
Have you ever tried Entity Framework for database access and dto creation?
Change your line to cmd.CommandType = CommandType.Text; instead of cmd.CommandType = CommandType.StoredProcedure;
Try this
string Sql = "select Company_ID,company_name from JO.dbo.Comp";
SqlConnection conn = new SqlConnection(connString);
SqlCommand cmd = new SqlCommand(Sql, conn);
cmd.CommandType = CommandType.Text;
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
da.Fill(ds);
for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
{
comboBox1.DataSource = ds.Tables[0];
comboBox1.DataTextField = "company_name";
comboBox1.DataValueField = "Company_ID";
comboBox1.DataBind();
comboBox1.Items.Insert(0, new ListItem("--Select--", "0"));
}
There is no use of for loop. you just need to check that whether the dataset contains rows or not.
string Sql = "select Company_ID,company_name from JO.dbo.Comp";
SqlConnection conn = new SqlConnection(connString);
SqlCommand cmd = new SqlCommand(Sql, conn);
cmd.CommandType = CommandType.Text;
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
da.Fill(ds);
if (ds.Tables[0].Rows.Count > 0)
{
comboBox1.DataSource = ds.Tables[0];
comboBox1.DataTextField = "company_name";
comboBox1.DataValueField = "Company_ID";
comboBox1.DataBind();
comboBox1.Items.Insert(0, new ListItem("Select", "0"));
}
string Sql = "select company_name from JO.dbo.Comp";
SqlConnection conn = new SqlConnection(connString);
SqlCommand cmd = new SqlCommand(Sql, conn);
cmd.CommandType = CommandType.StoredProcedure;
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
da.Fill(ds);
for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
comboBox1.Items.Add(ds.Tables[0].Rows[i][0].ToString());
public System.Data.DataTable EmployeeViewAll()
{
DataTable dtbl = new DataTable();
try
{
// Here it shuld be your database Connection String
string connectionString = "Server = .; database = HKS; Integrated Security = true";
using (SqlConnection sqlCon = new System.Data.SqlClient.SqlConnection(connectionString))
{
SqlDataAdapter SqlDa = new SqlDataAdapter("employeeViewAll", sqlCon);
SqlDa.SelectCommand.CommandType = CommandType.StoredProcedure;
SqlDa.Fill(dtbl);
}
return dtbl;
}
catch (Exception)
{
throw;
}
}
public void ComboFill()
{
DataTable dt = new DataTable();
eSP SP = new eSP();
d = SP.EmployeeViewAll();
comboBox1.DataSource = dt;
comboBox1.DisplayMember = "department";
comboBox1.ValueMember = "empName";
}
I need to get a database values to the p_cat combo box .....but i cannot pass the dataset inside the query..
class Datatbl_Class1
{
DataSet ds = new DataSet();
public DataSet filldata(string q)
{
string myconnection = "datasource=localhost;port=3306;username = root; password = 12345V";
MySqlConnection con = new MySqlConnection(myconnection);
MySqlCommand cmd = new MySqlCommand(q, con);
MySqlDataAdapter da = new MySqlDataAdapter(cmd);
da.Fill(ds);
return ds;
}
}
Select_int_Class1 s4 = new Select_int_Class1();
string q = "SELECT Sup_ID FROM gtec_computer.supplier WHERE Sup_Name='" +p_cmb_sup.Text+ "'";
string ww = "Sup_ID";
int t = s4.select_val_int(q, ww);
DataSet n = new DataSet();
Datatbl_Class1 dt = new Datatbl_Class1();
string Query = "SELECT Cat_ID FROM gtec_computer.supplier_detail WHERE Sup_Id="+t+" ";
n = dt.filldata(Query)
DataSet ds = new DataSet();
string myconnection = "datasource=localhost;port=3306;username = root; password = 12345V";
MySqlConnection con = new MySqlConnection(myconnection);
string q1 = "SELECT cat_Name FROM gtec_computer.category WHERE Cat_ID= " + n + " ";
MySqlCommand cmd = new MySqlCommand(q1, con);
MySqlDataAdapter da1 = new MySqlDataAdapter(cmd);
da1.Fill(ds);
p_cat.DataSource = ds;
You should be able to via parameter to the function call in the class... However, by building your command strings, you would be wide open for SQL-injection. Look into parameterized queries. Now, back to your original code and an alternative implementation...
class Datatbl_Class1
{
public DataSet filldata(string q )
{
string myconnection = "datasource=localhost;port=3306;username = root; password = 12345V";
MySqlConnection con = new MySqlConnection(myconnection);
MySqlCommand cmd = new MySqlCommand(q, con);
MySqlDataAdapter da = new MySqlDataAdapter(cmd);
DataSet ReturnThisOne = new DataSet();
da.Fill(ReturnThisOne);
return ReturnThisOne;
}
}
Just dont make the "ds" as a property of the class. Just create a new instance of a dataset within your method. It will be a pointer anyhow. Fill that and return the pointer to the calling source as you already are doing with your "n = dt.filldata(Query)". Yes, the function is no longer using the data table, but since it's reference is being returned, then the "n" location that is calling it will retain it. It won't get released to garbage collection until the function that "n" is in gets released.
Again, look into parameters to prevent sql-injection. But this should get you going.
I can't understand what I am doing wrong, I can't seem to SELECT with a prepared statement. However I can INSERT with a prepared statement.
MySqlCommand cmd = new MySqlCommand("SELECT * FROM code_post WHERE name = ?postRequired LIMIT 1", dbcon);
cmd.Parameters.Add(new MySqlParameter("?postRequired", requestString));
cmd.ExecuteNonQuery();
DataSet ds = new DataSet();
cmd.fill(ds, "result");
try {
thisBlog = ds.Tables["result"].Rows[0];
} catch {
invalid();
return;
}
Any advice on this would be greatly appreciated!
To fill a DataSet you will need a DataAdapter.
Try this:
MySqlCommand cmd = new MySqlCommand("SELECT * FROM code_post WHERE name = ?postRequired LIMIT 1", dbcon);
cmd.Parameters.Add(new MySqlParameter("?postRequired", requestString));
cmd.ExecuteNonQuery();
DataSet ds = new DataSet();
MySqlDataAdapter dAdap = new MySqlDataAdapter();
dAdap.SelectCommand = cmd;
dAdap.Fill(ds, "result");
try {
thisBlog = ds.Tables["result"].Rows[0];
} catch {
invalid();
return;
}
You need to use SqlDataAdapter
DataAdapter represents a set of data commands and a database connection that are used to fill the DataSet and update a SQL Server database.
The SqlDataAdapter provides this bridge by mapping Fill, which changes the data in the DataSet to match the data in the data source
Check the following syntax:
private static DataSet SelectRows(DataSet dataset,
string connectionString,string queryString)
{
using (SqlConnection connection =
new SqlConnection(connectionString))
{
SqlDataAdapter adapter = new SqlDataAdapter();
adapter.SelectCommand = new SqlCommand(
queryString, connection);
adapter.Fill(dataset);
return dataset;
}
}