Hey wish you all to have a happy holiday,
I am trying to display multiple query results from a SQL database table to a grid view control and a label. I have no problem with the grid view result, but the result from the ExecuteScalar command is not displaying inside my lable control with an ID="myCount". I could not figure out what went wrong with my code. I need your help.
protected void Page_Load(object sender, EventArgs e)
{
SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["MBSDB"].ConnectionString);
try {
conn.Open();
string query="SELECT * FROM tblBook";
using (SqlCommand mycmd = new SqlCommand(query, conn)) {
myGrid.DataSource = mycmd.ExecuteReader();
myGrid.DataBind();
}
string query2 = "SELECT count(title) FROM tblBook";
using (SqlCommand mycmd2 = new SqlCommand(query2, conn)) {
int count = (int)mycmd2.ExecuteScalar();
myCount.Text = count.ToString();
}
}
catch {
Exception(e);
}
finally { conn.Close(); }
}
Are you sure about there is no error. I think, the error occured and handling in the catch block and you are unaware of it.
You should change it;
(int)mycmd2.ExecuteScalar();
to
Convert.ToInt32(mycmd2.ExecuteScalar());
You can't unboxing an object like this; (int)mycmd2.ExecuteScalar()
Related
I have a DropDownList which gets it values from SQL table
I want to get the Average of the selected item (course in this case) from the dropDownList and to show it in a label :
This section works -
SqlConnection sqlConnection1;
sqlConnection1 = new SqlConnection(#"Data Source=HA\SQLEXPRESS; Initial Catalog=Grades1; Integrated Security=True");
SqlCommand Command = null;
Command = new SqlCommand("SELECT Course FROM GradesTable1", sqlConnection1);
Command.Connection.Open();
SqlDataAdapter dataAdapter = new SqlDataAdapter(Command);
DataTable dataTble1 = new DataTable();
dataAdapter.Fill(dataTble1);
if (dataTble1.Rows.Count > 0)
{
foreach (DataRow row in dataTble1.Rows)
{
ListItem course1 = new ListItem(row["Course"].ToString());
if (!DropDownList1.Items.Contains(course1))
{
DropDownList1.Items.Add(course1); // showing the 2 courses
}
}
}
Command.Connection.Close();
}
}
Here is the problem - (I get nothing, no data )
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
SqlConnection sqlConnection1;
sqlConnection1 = new SqlConnection(#"Data Source=HA\SQLEXPRESS; Initial Catalog=Grades1; Integrated Security=True");
SqlCommand Command = null;
Command = new SqlCommand($"SELECT AVG(Grade) FROM GradesTable1 WHERE Course = #course", sqlConnection1);
Command.Parameters.AddWithValue("#course", DropDownList1.SelectedItem);
Command.Connection.Open();
SqlDataReader sqlDataReader1 = Command.ExecuteReader();
if (sqlDataReader1.Read())
{
LabelAverage.Text = sqlDataReader1[0].ToString();
}
else
{
LabelAverage.Text = "No Data"; // doesn't get into here anyhow
}
}
EDIT
I tried several variations as $"SELECT AVG(Grade) AS "ClassAVG" FROM GradesTable1 WHERE Course = #course" and Command.Parameters.AddWithValue("#course", DropDownList1.SelectedItem.Text), or DropDownList1.SelectedValue
I believe the problem is with the DropDownlist values which being received from the SQL and are not hard coded.
Is there a correct way to this? is it possible without knowing what are the "Courses" in advanced?
Thanks for the answers, feel free to give your opinion.
I found out what was missing in the DropDownList in aspx page (not the aspx.cs page) -the AutoPostBack="true"
Adding that to DropDownList solved the problem.
// query = Sql query
query.Select(s => new MusteriNoktaComboItemDTO
{
Label = s.Adi,
Value = s.ID.ToString()
}).ToList();
I need to use a variable (edifcodigo) which assigned value is retrieved from one query to insert it in a table by using other query but there is a error that says this variable is not available in actual context. I'm kind of new in aspnet, could anybody know how to figure this out?
This is the code I have:
//Connect to db
string connetionString = #"myconexionstring";
string sql = "SELECT TOP 1 id_proyecto AS codigo FROM DNN_SCO_PROY_CO_PROYECTO_TBL WHERE nombre_proyecto= '"+ uedif +"'";
//find building code by querying the database
try
{
using (SqlConnection conexion = new SqlConnection(connetionString))
{
conexion.Open();
using (SqlCommand query = new SqlCommand(sql, conexion))
{
SqlDataReader result = query.ExecuteReader();
while (result.Read())
{
string edifcodigo = result["codigo"].ToString();
}
}
}
}
catch (Exception ex)
{
Response.Write(ex.Message);
}
//Save referer friend
try
{
using (SqlConnection conn = new SqlConnection(connetionString))
{
conn.Open();
using (SqlCommand cmd = new SqlCommand("DNN_SVI_SCO_DATOS_RECOMIENDA_AMIGO_SP", conn))
{
cmd.CommandType = System.Data.CommandType.StoredProcedure;
cmd.Parameters.Add("#DRA_PROYECTO_CLIENTE", System.Data.SqlDbType.VarChar).Value = edifcodigo; ;
}
}
}
catch (Exception ex)
{
Response.Write(ex.Message);
}
That's because you declared the variable inside a different code block. Every time you open a curly bracket, you open a new code block. Every time you close the curly bracket, you close the current code block. Each code block have it's own scope - it can access variables declared in the surrounding code block, but not variables declared in "sibling" code blocks.
Also, please read about parameterized queries and how they protect you from SQL injection, and change your queries accordingly.
Also, you don't need to close the connection between the two commands, and you can reuse a single command instance in this case. Here is an improved version of your code:
//Connect to db
var connetionString = #"myconexionstring";
var sql = "SELECT TOP 1 id_proyecto AS codigo FROM DNN_SCO_PROY_CO_PROYECTO_TBL WHERE nombre_proyecto = #nombre_proyecto";
//find building code by querying the database
try
{
using (var conexion = new SqlConnection(connetionString))
{
conexion.Open();
using (var cmd = new SqlCommand(sql, conexion))
{
cmd.Parameters.Add("#nombre_proyecto", SqlDbType.NVarChar).Value = uedif;
var edifcodigo = cmd.ExecuteScalar();
//Save referer friend
cmd.Parameters.Clear();
cmd.CommandText = "DNN_SVI_SCO_DATOS_RECOMIENDA_AMIGO_SP";
cmd.CommandType = System.Data.CommandType.StoredProcedure;
cmd.Parameters.Add("#DRA_PROYECTO_CLIENTE", System.Data.SqlDbType.VarChar).Value = edifcodigo; ;
}
}
}
catch (Exception ex)
{
Response.Write(ex.Message);
}
You are declaring the string variable inside your while loop, it loses scope once you exit the while loop, move it's declaration above with:
string connetionString = #"myconexionstring";
string sql = "SELECT TOP 1 id_proyecto AS codigo FROM DNN_SCO_PROY_CO_PROYECTO_TBL WHERE nombre_proyecto= '"+ uedif +"'";
string edifcodigo = "";
You are trying to use a variable that declared in another scope. edifcodigo should be declared in the parent scope of both try blocks.
//Connect to db
string connetionString = #"myconexionstring";
string sql = "SELECT TOP 1 id_proyecto AS codigo FROM DNN_SCO_PROY_CO_PROYECTO_TBL WHERE nombre_proyecto= '"+ uedif +"'";
string edifcodigo=""; // YOU SHOULD DECLARE edifcodigo HERE
and than rest of code will come
//find building code by querying the database
try
{
using (SqlConnection conexion = new SqlConnection(connetionString))
{
conexion.Open();
using (SqlCommand query = new SqlCommand(sql, conexion))
{
SqlDataReader result = query.ExecuteReader();
while (result.Read())
{
edifcodigo = result["codigo"].ToString();
}
}
}
}
catch (Exception ex)
{
Response.Write(ex.Message);
}
//Save referrer friend
try
{
using (SqlConnection conn = new SqlConnection(connetionString))
{
conn.Open();
using (SqlCommand cmd = new SqlCommand("DNN_SVI_SCO_DATOS_RECOMIENDA_AMIGO_SP", conn))
{
cmd.CommandType = System.Data.CommandType.StoredProcedure;
cmd.Parameters.Add("#DRA_PROYECTO_CLIENTE", System.Data.SqlDbType.VarChar).Value = edifcodigo; ;
}
}
}
catch (Exception ex)
{
Response.Write(ex.Message);
}
I am stuck with this problem since yesterday. I have created a button, which when clicked display the results from a SQL Server table. I thought of using MessageBox to print these results or if there is any other way to print results?
private void button1_Click(object sender, EventArgs e)
{
try
{
SqlConnection con = new SqlConnection("Data Source=FAREEDH;Initial Catalog=DeakinsTrade;Integrated Security=True");
SqlCommand command = new SqlCommand("SELECT * FROM Products", con);
con.Open();
SqlDataReader reader = command.ExecuteReader();
command.ExecuteNonQuery();
con.Close();
}
catch (Exception es)
{
MessageBox.Show(es.Message);
}
}
I have tried different methods but it never worked.. I am really stuck. If you want more details, let me know. Thanks for the help in advance
Add a datagridview control to show multiple rows and try this code and rename it what you want and replace this YourDataGridVeiwName from the name you set for datagridview control and try below code
private void button1_Click(object sender, EventArgs e)
{
try
{
string connectionString = "Data Source=FAREEDH;Initial Catalog=DeakinsTrade;Integrated Security=True";
string query = "SELECT ProductName FROM Products;";
using (SqlConnection con = new SqlConnection(connectionString))
using (SqlCommand command = new SqlCommand(query, con))
{
con.Open();
using (SqlDataAdapter sda = new SqlDataAdapter(command))
{
DataTable dt = new DataTable();
sda.Fill(dt);
YourDataGridVeiwName.DataSource= dt;
}
con.Close();
}
}
catch (Exception es)
{
MessageBox.Show(es.Message);
}
}
You need to use the SqlDataReader and iterate over the rows returned, extract what you need from each row, and then display that to the enduser.
I modified your code a bit, to make it safer (using blocks!), and I modified the query to return only the product name (assuming you have that) since you cannot really display a whole row in a message box....
private void button1_Click(object sender, EventArgs e)
{
try
{
string connectionString = "Data Source=FAREEDH;Initial Catalog=DeakinsTrade;Integrated Security=True";
string query = "SELECT ProductName FROM Products;";
using (SqlConnection con = new SqlConnection(connectionString))
using (SqlCommand command = new SqlCommand(query, con))
{
con.Open();
using (SqlDataReader reader = command.ExecuteReader())
{
while (reader.Read())
{
string productName = reader.GetFieldValue<string>(0);
MessageBox("Product is: " + productName);
}
reader.Close();
}
con.Close();
}
}
catch (Exception es)
{
MessageBox.Show(es.Message);
}
}
i have this code:
private void btGuardar_Click(object sender, EventArgs e)
{
if (txDescrip.Text.Trim().Equals("") == false && txPath.Text.Trim().Equals("") == false)
{
try
{
byte[] imgData = getMyFileBytes(txPath.Text);
//Server connection
OleDbConnection connection = new OleDbConnection(strcx);
String q = "INSERT INTO MisImagenes (Id,CustomImage) values(#MyPath, #ImageData)";
//Initialize sql command object for insert
OleDbCommand command = new OleDbCommand(q, connection);
//We are passing original image path and image byte data as sql parameters
OleDbParameter pMyPath = new OleDbParameter("#MyPath", (object)txPath.Text);
OleDbParameter pImgData = new OleDbParameter("#ImageData", (object)imgData);
command.Parameters.Add(pMyPath);
command.Parameters.Add(pImgData);
//Open connection and execute insert query
connection.Open();
command.ExecuteNonQuery();
connection.Close();
Mensaje.aviso("Imagen Guardada :)");
//Limpiamos
clearAlta();
}
catch (Exception exc)
{
Mensaje.aviso("Something went wrong! :( " + exc.Message);
}
}
}
when i execute this says "Must declare the scalar variable "#MyPath"." ... any help? please, thank you.
I'm just trying to save an image to my sqlserver db by selecting the path and id description for the image. and i just get this frustrating error
you should use '?' instead of parameter names in oledb queries
INSERT INTO MisImagenes (Id,CustomImage) values(?, ?)
similar question and answer: OleDbCommand parameters order and priority
I use this pgm to get value from a column in xmlstring format named partinfo.which is one of the columns in table test.the partinfo column can be treated as another table containing many columns.and i want to read data from one of this column which is installed date in this case.but while executing i am getting a
sql exception: Cannot find either column "partinfo" or the user-defined
function or aggregate "partinfo.query", or the name is ambiguous.how
can i solve this.
namespace WpfApplication1
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
try {
SqlConnection con = new
SqlConnection("Data Source=NIP007\\SQLEXPRESS;
Initial Catalog=test;User ID=sa;Password=nest123#!");
con.Open();
string query = "SELECT [partinfo].query('.//InstalledDate').value('.','VARCHAR(MAX)')FROM [test]";
SqlCommand cmd = new SqlCommand(query, con);
// StringBuilder builder=new StringBuilder();
// string PartInfo=string.Empty;
SqlDataReader dr = cmd.ExecuteReader();
while (dr.Read())
{
string str5 =dr.ToString();
if (!string.IsNullOrEmpty(str5))
{
textBox1.Text=str5;
}
}
}
catch(Exception ex)
{
}
}
}
}
It is not clear what exactly where your error lies because, your SQL should work ok (Demo Here) and not return an error, although I am not sure the output is what you would want as it just concatenates all the installed dates in the XML as one long string:
As said in my previous answer if you have multiple Installed Dates per row, you will want to use CROSS APPLY TO get the installed dates as separate rows.
Demo SQL using CROSS APPLY
If you really want the dates concatenated to one string then I'd suggest using a string builder to do this:
try
{
string query = #"SELECT InstalledDate = x.value('InstalledDate[1]', 'DATETIME')
FROM dbo.Test
CROSS APPLY PartInfo.nodes('/DocumentElement/PartInfo') p (x);";
using (var con = new SqlConnection("Data Source=NIP007\\SQLEXPRESS;Initial Catalog=test;User ID=sa;Password=nest123#!"))
using (var cmd = new SqlCommand(query, con))
{
con.Open();
using (var dr = cmd.ExecuteReader())
{
var builder = new StringBuilder();
while (dr.Read())
{
string str5 = dr.GetString(0);
if (!string.IsNullOrEmpty(str5))
{
builder.Append(str5 + ",");
}
}
textBox1.Text = builder.ToString();
}
}
}
catch (Exception ex)
{
}
If this doesn't help can you post the DDL of your table Test and some sample data.
Thanks