Below is my code to get data from my oracle database to display a table with multiple rows in asp.net(C#). Te columns will be Name, Section and Gender. The headers of the table are hardcoded, only rows' data should be populated from database. On executing the code, I am getting only 1st row coming from database. Remaining rows are not coming. Please suggest for the solution.
public void GetDailyData()
{
using (OracleConnection conn = new OracleConnection(ConfigurationManager.ConnectionStrings["dataconn"].ToString()))
{
try
{
string query = #"SELECT name,section, gender FROM t_student WHERE order by TRUNC(admissionDate)";
OracleCommand cmd = new OracleCommand(query, conn);
conn.Open();
OracleDataAdapter da = new OracleDataAdapter(cmd);
DataSet ds = new DataSet();
cmd.ExecuteNonQuery();
da.Fill(ds);
foreach (DataRow dr in ds.Tables[0].Rows)
{
if (ds.Tables[0].Rows.Count > 0)
{
LabelName.Text = ds.Tables[0].Rows[0].Field<string>(0);
LabelSection.Text = ds.Tables[0].Rows[0].Field<string>(1) ;
LabelGender.Text = ds.Tables[0].Rows[0].Field<string>(2) ;
}
}
}
catch (Exception ex)
{
throw ex;
}
}
}
You're only seeing row data from the first row because that's what you're pulling out when you say ds.Tables[0].Rows[0] - Rows[0] will always be the first row of the table
This entire block of code is confused;
you cannot show multiple rows using single labels - Use a Grid component and DataBind it to the datatable.
The code uses a loop to go through table rows but checks if the table has rows, inside the loop ( the loop won't run if it doesn't) and instead of using the enumerated row it always access the first row on every pass of the loop.
Do not use a DataSet, just make a new DataTable and fill it - datasets are for when you want to work with multiple related datatables and in this case of a single table are a useless extra layer.
Do not ExecuteNonQuery on the command, it's a useless operation - the dataadapter will execute the query during the fill, you don't need to do it (and ExecuteNonQuery is for insert/update/delete/create etc - this is a select).
Your code could/should look more like:
DataTable dt = new DataTable();
da.Fill(dt);
gridControl.DataSource = dt;
gridControl.DataBind();
That's it. All the rest of the code (apart from the command and connection) should be thrown away
Related
I'm currently using Mono on Ubuntu with MonoDevelop, running with a DataTable matching a table in the database, and should be attempting to update it.
The code following uses a Dataset loaded from an XML file, which was created from a Dataset.WriteXML on another machine.
try
{
if(ds.Tables.Contains(s))
{
ds.Tables[s].AcceptChanges();
foreach(DataRow dr in ds.Tables[s].Rows)
dr.SetModified(); // Setting to modified so that it updates, rather than inserts, into the database
hc.Data.Database.Update(hc.Data.DataDictionary.GetTableInfo(s), ds.Tables[s]);
}
}
catch (Exception ex)
{
Log.WriteError(ex);
}
This is the code for inserting/updating into the database.
public override int SQLUpdate(DataTable dt, string tableName)
{
MySqlDataAdapter da = new MySqlDataAdapter();
try
{
int rowsChanged = 0;
int tStart = Environment.TickCount;
da.SelectCommand = new MySqlCommand("SELECT * FROM " + tableName);
da.SelectCommand.Connection = connection;
MySqlCommandBuilder cb = new MySqlCommandBuilder(da);
da.UpdateCommand = cb.GetUpdateCommand();
da.DeleteCommand = cb.GetDeleteCommand();
da.InsertCommand = cb.GetInsertCommand();
da.ContinueUpdateOnError = true;
da.AcceptChangesDuringUpdate = true;
rowsChanged = da.Update(dt);
Log.WriteVerbose("Tbl={0},Rows={1},tics={2},", dt.TableName, rowsChanged, Misc.Elapsed(tStart));
return rowsChanged;
catch (Exception ex)
{
Log.WriteError("{0}", ex.Message);
return -1
}
I'm trying the above code, and rowsChanged becomes 4183, the number of rows I'm editing. However, when I use HeidiSQL to check the database itself, it doesn't change anything at all.
Is there a step I'm missing?
Edit: Alternatively, being able to overwrite all rows in the database would work as well. This is a setup for updating remote computers using USB sticks, forcing it to match a source data table.
Edit 2: Added more code sample to show the source of the DT. The DataTable is prefilled in the calling function, and all rows have DataRow.SetModified(); applied.
Edit 3: Additional information. The Table is being filled with data from an XML file. Attempting fix suggested in comments.
Edit 4: Adding calling code, just in case.
Thank you for your help.
The simplest way which you may want to look into might be to TRUNCATE the destination table, then simply save the XML import to it (with AI off so it uses the imported ID if necessary). The only problem may be with the rights to do that. Otherwise...
What you are trying to do can almost be handled using the Merge method. However, it can't/won't know about deleted rows. Since the method is acting on DataTables, if a row was deleted in the master database, it will simply not exist in the XML extract (versus a RowState of Deleted). These can be weeded out with a loop.
Likewise, any new rows may get a different PK for an AI int. To prevent that, just use a simple non-AI PK in the destination db so it can accept any number.
The XML loading:
private DataTable LoadXMLToDT(string filename)
{
DataTable dt = new DataTable();
dt.ReadXml(filename);
return dt;
}
The merge code:
DataTable dtMaster = LoadXMLToDT(#"C:\Temp\dtsample.xml");
// just a debug monitor
var changes = dtMaster.GetChanges();
string SQL = "SELECT * FROM Destination";
using (MySqlConnection dbCon = new MySqlConnection(MySQLOtherDB))
{
dtSample = new DataTable();
daSample = new MySqlDataAdapter(SQL, dbCon);
MySqlCommandBuilder cb = new MySqlCommandBuilder(daSample);
daSample.UpdateCommand = cb.GetUpdateCommand();
daSample.DeleteCommand = cb.GetDeleteCommand();
daSample.InsertCommand = cb.GetInsertCommand();
daSample.FillSchema(dtSample, SchemaType.Source);
dbCon.Open();
// the destination table
daSample.Fill(dtSample);
// handle deleted rows
var drExisting = dtMaster.AsEnumerable()
.Select(x => x.Field<int>("Id"));
var drMasterDeleted = dtSample.AsEnumerable()
.Where( q => !drExisting.Contains(q.Field<int>("Id")));
// delete based on missing ID
foreach (DataRow dr in drMasterDeleted)
dr.Delete();
// merge the XML into the tbl read
dtSample.Merge(dtMaster,false, MissingSchemaAction.Add);
int rowsChanged = daSample.Update(dtSample);
}
For whatever reason, rowsChanged always reports as many changes as there are total rows. But changes from the Master/XML DataTable do flow thru to the other/destination table.
The delete code gets a list of existing IDs, then determines which rows needs to be deleted from the destination DataTable by whether the new XML table has a row with that ID or not. All the missing rows are deleted, then the tables are merged.
The key is dtSample.Merge(dtMaster,false, MissingSchemaAction.Add); which merges the data from dtMaster with dtSample. The false param is what allows the incoming XML changes to overwrite values in the other table (and eventually be saved to the db).
I have no idea whether some of the issues like non matching AI PKs is a big deal or not, but this seems to handle all that I could find. In reality, what you are trying to do is Database Synchronization. Although with one table, and just a few rows, the above should work.
I have 2 DataTables: 1 that is filled with all the data from a table in my database called Ticket_Report, and a second one that is filled with new tickets.
I am searching the Ticket_report datatable for duplicates from the new ticket DataTable (and deleting them). Then I merge the new tickets datatable into the Ticket_report datatable.
I then try and Update the Ticket_Report table in SQL Server with the newly edited Ticket_report datatable. I am expecting the Update method to Update the table in SQL Server with rows that have matching primary keys from the datatable, and Insert rows that don't exist.
I am not getting any errors, however it doesn't seem like the rows are being updated/inserted.
con.Open();
DataTable ticketReportDT = new DataTable();
ticketReportDT = newTicketdt.Clone();
ticketReportDT.Columns[0].Unique = true;
SqlCommand cmd2 = new SqlCommand("SELECT * FROM ticket_report", con);
SqlDataAdapter da = new SqlDataAdapter(cmd2);
da.Fill(ticketReportDT);
da.UpdateCommand = new SqlCommandBuilder(da).GetUpdateCommand();
int currentTicketCount = ticketReportDT.Rows.Count;//3234
int newTicketCount = newTicketdt.Rows.Count; //339
//Removing Duplicate tickets in ticketReportDt
foreach (DataRow NewTicketsRow in newTicketdt.Rows)
{
foreach (DataRow currentTicketsRow in ticketReportDT.Select())
{
if (currentTicketsRow.Field<string>(ticketReportDT.Columns[0]) == NewTicketsRow.Field<string>(newTicketdt.Columns[0]))
{
currentTicketsRow.Delete();
}
}
}
ticketReportDT.AcceptChanges();
int currentTicketCount2 = ticketReportDT.Rows.Count;//2903, is less than last count because duplicates removed
ticketReportDT.Merge(newTicketdt);//add new tickets to ticketReportDT
ticketReportDT.AcceptChanges();
int currentTicketCount3 = ticketReportDT.Rows.Count;//3242, count went up because new tickets added
da.Update(ticketReportDT);//apply changes to database table Ticket_Report
con.Close();
Console.WriteLine("Ticket Transfer Complete");
This runs without error. To test, I did a count query in SQL Server before and after this update.
Before update:
select count(*) from TICKET_REPORT
// = 3234
After Update:
select count(*) from TICKET_REPORT
// = 3234 <-Should be 3242 (row count of ticketReportDT)
It seems like the Datatable has the correct amount of rows, but when I do the update, this does not reflect in SQL Server. Am I doing something wrong?
Since you have called ticketReportDT.AcceptChanges() before updating database it is not going to update anything in the database.
i want to create a for loop in which i want to write a query which updates the the value of each row in database. the rows are present in the datagridview as well as in the database. the aim is when the changes are made in datagridview so using a button the change are also applied in the database table too. in each row the barcode and its quantity is different. if the changes are made in all the rows in datagridview so it is also to be applied in database using button and also please help with the parameters.
here is the query which should be considered in the for loop:
SqlCommand cmd2 = new SqlCommand("update prod_info set item_quantity=#qty where barcode=#barcode ", con);
consider barcode as column1 and item_quantity as column2.
so far to create a for loop i have tried this but getting error in the for loops:
for (int i = 0; dataGridView2.Rows.Count; i++) //getting error here
{
SqlCommand cmd2 = new SqlCommand("update prod_info set item_quantity=#qty where barcode=#barcode ", con);
cmd2.Parameters.AddWithValue("#barcode", dataGridView2.Rows[i].Cells[1].Value.ToString());
cmd2.Parameters.AddWithValue("#qty", dataGridView2.Rows[i].Cells[1].Value.ToString());
}
you should call cmd2.ExecuteNonQuery(); in your loop ... otherwise no sql commands will be executed
to get a better solution you should move to creation of cmd2 before the loop. also add the parameters there (without assigning values) ... inside the loop just assign the values and call ExecuteNonQuery.
maybe the best solution would be to use databinding and a SqlDataAdapter with assigned UpdateCommand.
just saw that there probably is an error in your code ... you use the value from Cell[1] for both of your parameters ...
example:
first create a DataTable ... var dt = new DataTable();
then add the columns you want in your grid to the DataTable ... dt.Columns.Add("xyz");
then attach the DataTable to your grid: dataGridView2.DataSource = dt;
now you should be able to edit the contents of column "xyz". to write the values to the database you create a SqlDataAdapter ... var adp = new SqlDataAdapter();
then set adp.InsertCommand = new SqlCommand(...) and adp.UpdateCommand = new SqlCommand(...)
now you can call adp.Update(); and all the values from your grid are written to db ... for newly added rows the InsertCommand is invoked and for edited rows the UpdateCommand is invoked.
I am using .net 3.5 . I have a database on which i want to run queries. I am using data adapters or SqlCommand to run the query. But eventually I want the data in row-wise and column-wise string data. What is the way to do that ?
I mean how to extract the data in this way from the dataset(whuich is what is returned by sqlDataAdapter) ? Or is there some other approach to this problem ?
You should look into the DataSet class.
DataSet dataset = new DataSet();
SqlDataAdapter adapter = new SqlDataAdapter();
adapter.SelectCommand = new SqlCommand(
queryString, connection);
adapter.Fill(dataset);
You access values by method of:
DataSet.Tables["tableName"].Rows[rowIndex]["columnName"]
Or alternatively:
foreach(DataTable table in dataSet.Tables)
{
foreach(DataRow row in table.Rows)
{
foreach (DataColumn column in table.Columns)
{
//Do something with
row[column];
}
}
}
Well, you could go the cheap way and use foreach to iterate through the Rows in the specified Table in the DataSet.
foreach(DataRow myRow in myDataSet.Tables[n].Rows) { ... }
Edit: Must have been typing this at the same time as the other guy :) You wanted string data. You'll probably have to use myRow[columnIndex].ToString() since it will be an Object type of some sort.
Also, if you just need one string from the database, may I suggest you write a query that does the concatenation server-side, and a wrapper function that gets myDataSet.Tables[0].Rows[0].ToString();
I have a postgresql db and a C# application to access it. I'm having a strange error with values I return from a NpgsqlDataAdapter.Fill command into a DataSet.
I've got this code:
NpgsqlCommand n = new NpgsqlCommand();
n.Connection = connector; // a class member NpgsqlConnection
DataSet ds = new DataSet();
DataTable dt = new DataTable();
// DBTablesRef are just constants declared for
// the db table names and columns
ArrayList cols = new ArrayList();
cols.Add(DBTablesRef.all); //all is just *
ArrayList idCol = new ArrayList();
idCol.Add(DBTablesRef.revIssID);
ArrayList idVal = new ArrayList();
idVal.Add(idNum); // a function parameter
// Select builder and Where builder are just small
// functions that return an sql statement based
// on the parameters. n is passed to the where
// builder because the builder uses named
// parameters and sets them in the NpgsqlCommand
// passed in
String select = SelectBuilder(DBTablesRef.revTableName, cols) +
WhereBuilder(n,idCol, idVal);
n.CommandText = select;
try
{
NpgsqlDataAdapter da = new NpgsqlDataAdapter(n);
ds.Reset();
// filling DataSet with result from NpgsqlDataAdapter
da.Fill(ds);
// C# DataSet takes multiple tables, but only the first is used here
dt = ds.Tables[0];
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
So my problem is this: the above code works perfectly, just like I want it to. However, if instead of doing a select on all (*) if I try to name individual columns to return from the query I get the information I asked for, but rather than being split up into seperate entries in the data table I get a string in the first index of the data table that looked something like:
"(0,5,false,Bob Smith,7)"
And the data is correct, I would be expecting 0, then 5, then a boolean, then some text etc. But I would (obviously) prefer it to not be returned as just one big string.
Anyone know why if I do a select on * I get a datatable as expected, but if I do a select on specific columns I get a data table with one entry that is the string of the values I'm asking for?
Ok, I figured it out, it was in the SelectBuilder function. When more than one column was listed in the select statement it was wrapping the columns in ()'s, and apparently this causes either postgreSQL or Npgsql to interpret that as a desire to return a list in string form.