Develop Reference

SqlDataAdapter, SqlBulkCopy and DataTable with NetTopologySuite.IO.SqlServerBytes

I am trying to use SqlBulkCopy with .net core, but since I use a geometry column the following code requires Microsoft.SqlServer.Types which is not fully .net core compatible, especially on Linux.
using (SqlDataAdapter adapter = new SqlDataAdapter("SELECT TOP 0 * FROM " + tableName, sqlConnection))
{
DataTable dt = new DataTable();
adapter.Fill(dt);
return dt;
}
Without the dependency the Fill() fails as it cannot find the type.
Normally I use NetTopologySuite.IO.SqlServerBytes, but in this case the magic happens somewhere in the SqlDataAdapter and I don't know how to overwrite it.
I tried to create the DataTable columns manually without using Fill(), but it seems whatever type I specify I later get an error in the SqlBulkCopy.
The given value of type XYZ from the data source cannot be converted to type udt of the specified target column
I tried with SqlBytes and byte[], but nothing seems to work.
Update 1:
I got it working with a manually created DataTable with byte[] as the type for that column.
Still it would be nice to have a way using adapter.Fill(dt); or similar so that I do not have to manually list all the columns.

using (SqlDataAdapter da = new SqlDataAdapter("SELECT TOP 5 * FROM " + tableName, sqlConnection)
{
using (SqlCommandBuilder builder = new SqlCommandBuilder(da))
{
DataTable dt = new DataTable();
DataSet dataSet = new DataSet();
dt = dgPurchase.DataSource as DataTable;
//here assign the data table
da.Fill(dataSet, dt);
da.UpdateCommand = builder.GetUpdateCommand(true);
//da.InsertCommand = builder.GetInsertCommand(true);
//If new row then open it
da.Update(dataSet, dt);
}
}
// Can update though parameters .Follow the link
https://learn.microsoft.com/en-us/dotnet/framework/data/adonet/updating-data-sources-with-dataadapters
//Useing inline code .Follow the link
http://csharp.net-informations.com/dataadapter/updatecommand-sqlserver.htm

c# How to clear oledbconnection cache, multiple excel queries erroring out

Sorry for the vague title but I'm not sure how best to word it.
Basically, the issue that I'm having is that I initially was using an oledbconnection in C# to initiate a connection to a spreadsheet, query it, and load the results into a .net datatable. Unfortunately, it maxes out at 255 fields which I have around 600.
So, what I did instead was I created a dataset and tried to load 4 separate data tables with separate queries. Now for some reason, what's crazy to me is, if I load lets say, the first data table with 190 fields, and then I go on to query the spreadsheet again, if I go over that 250 mark (which I'd have 60 left), I get the following error:
An exception of type 'System.Data.OleDb.OleDbException' occurred in System.Data.dll but was not handled in user code
Additional information: No value given for one or more required parameters.
If I reduce the amount of fields in the second table to equal less than 250 though, it works. Anyway, is there a way that I can somehow clear the cache of the oledbconnection to somehow drop the first 190 fields or whatever is holding the result of the excel query so I can move on to the next? I tried doing a data adapter dispose but that didn't work, same issue. If I do a connection.dispose, I have to re-initialize the connection anyway. Is there a way I can still do this without having to drop the connection? Code below:
OleDbConnection cnn = new OleDbConnection(Settings.ExcelCN);
OleDbCommand fillT1 = new OleDbCommand(Settings.Excel_Proj_Select_1, cnn);
OleDbCommand fillT2 = new OleDbCommand(Settings.Excel_Proj_Select_2, cnn);
OleDbCommand fillT3 = new OleDbCommand(Settings.Excel_Proj_Select_3, cnn);
OleDbCommand fillT4 = new OleDbCommand(Settings.Excel_Proj_Select_4, cnn);
OleDbCommand updateCnt = new OleDbCommand(Settings.Excel_Update_Count_Select, cnn);
cnn.Open();
OleDbDataAdapter adp1 = new OleDbDataAdapter(fillT1);
OleDbDataAdapter adp2 = new OleDbDataAdapter(fillT2);
OleDbDataAdapter adp3 = new OleDbDataAdapter(fillT3);
OleDbDataAdapter adp4 = new OleDbDataAdapter(fillT4);
DataTable dt1 = new DataTable();
DataTable dt2 = new DataTable();
DataTable dt3 = new DataTable();
DataTable dt4 = new DataTable();
DataSet ds1 = new DataSet();
adp1.Fill(dt1);
ds1.Tables.Add(dt1);
adp2.Fill(dt2);
ds1.Tables.Add(dt2);
adp3.Fill(dt3);
ds1.Tables.Add(dt3);
adp4.Fill(dt4);
ds1.Tables.Add(dt4);
int rowcount = updateCnt.ExecuteNonQuery();
cnn.Close();

DataTable Load very slow

I'm using a datatable as the datasource of some dropdowns on a page, but have noticed that the page is very slow during the postbacks.
I've tracked it through to here:
DataTable dt = new DataTable();
dt.Load(sqlCmd.ExecuteReader()); // this takes ages
The sql command is a parametrised query, not a stored procedure (the return values and where are quite 'dynamic' so this wouldn't be practicable), but nevertheless a simple select union query.
Usually returns between 5 and 20 options per dropdown, depending on what's been selected on the other dropdowns.
When I run the query in the management studio, it's done in under a second. Here it can take up to 7 seconds per dropdown, with 6 dropdowns on the page it soon adds up.
I have also tried with a SqlDataAdapter:
SqlDataAdapter sqlDa = new SqlDataAdapter(sqlCmd);
sqlDa.Fill(dt); // this takes ages
but this was just as slow.
I have this on 2 different systems and on both have the same performance issues.
If anyone knows a better (faster) methord, or knows why this is so slow that would be great.

Not the best thread I've seen on the issue, but there's good links inside, & it's in my post history:
SQL Query that runs fine in SSMS runs very slow in ASP.NET
The SQL Optimizer sometimes likes to decide what's best & you'll have to break out your query through some tracing and logging of data execution plans. It may very well be something as buried as a bad index, or your query code might need optimization. Seeing as we don't have the query code, and having it may or may not be helpful. I'd recommend you follow the guides linked to in the above post and close your question.

here is an example on how you can load a DataTable very quickly notice how I show specific Columns that I want to return
private DataTable GetTableData()
{
string sql = "SELECT Id, FisrtName, LastName, Desc FROM MySqlTable";
using (SqlConnection myConnection = new SqlConnection(connectionString))
{
using (SqlCommand myCommand = new SqlCommand(sql, myConnection))
{
myConnection.Open();
using (SqlDataReader myReader = myCommand.ExecuteReader())
{
DataTable myTable = new DataTable();
myTable.Load(myReader);
myConnection.Close();
return myTable;
}
}
}
}
If you want to use DataAdapter to Fill the DataTable here is a simple example
private void FillAdapter()
{
using (SqlConnection conn = new SqlConnection(Your ConnectionString))
{
conn.Open();
using (SqlDataAdapter dataAdapt = new SqlDataAdapter("SELECT * FROM EmployeeIDs", conn))
{
DataTable dt = new DataTable();
dataAdapt.Fill(dt);
// dataGridView1.DataSource = dt;//if you want to display data in DataGridView
}
}
}

Trying to load a DataSet, but it is always null. Regular sqlReader.GetValue() is not

I don't use DataSets much. Usually find myself using an ORM or just a basic sqlReader.Read() followed by some GetValues(). I'm working on some legacy code that has DataSets all over the place, and while fixing a bug was trying to DRY some of it up.
However, I can't seem to actually get the data loaded into a non-typed DataSet.
public static DataSet ExecuteStoredProcedure(string storedProcedure, DBEnum db, IEnumerable<SqlParameter> parameters)
{
DataSet result = new DataSet();
using (SqlConnection connection = SqlHelper.GetSqlConnection(db))
{
SqlCommand command = connection.CreateCommand();
command.CommandType = CommandType.StoredProcedure;
command.CommandText = storedProcedure;
if (parameters != null)
foreach (SqlParameter parameter in parameters)
command.Parameters.Add(parameter);
connection.Open();
DataTable table = new DataTable();
using (SqlDataReader reader = command.ExecuteReader())
{
table.Load(reader);
}
result = table.DataSet; // table.DataSet is always empty!
}
return result;
}
I assumed table.Load(reader) does all the necessary reader.Read() calls ... but I went ahead and tried it both with and without reader.Read() before the table.Load(), to no avail.
I know that the stored procedure being called is actually returning data. If I do something like this, I see the data just fine:
using(SqlDataReader reader = command.ExecuteReader())
{
reader.Read();
object test = reader.GetValue(0); // returns the expected value
}
Seems like I'm missing something simple here, but I've been scratching my head over this one for a while now.
This is in .NET 3.5.

If you can, I would suggest using a SqlDataAdapter to populate the DataTable
using(SqlDataAdapter sqlDA = new SqlDataAdapter(command))
{
sqlDA.Fill(table);
}

You logic shows the DataTable being loaded with data from the reader but DataTable is never added to a dataset.

I believe the dataset should be created first. In fact, you could use DataSet.Load instead of the DataTable.Load. The DataSet.Load should create data tables, but it won't work the other way around.

A DataSet contains DataTables not the other way round. So if you want to create a DataSet to return then you'll probably want to create a new dataset and then add your DataTable into it before returning it. If a DataTable is not in a DataSet then the reference to its parent dataset will always be null.
That having been said I do also recommend Jason Evans' suggestion of using teh SqlDataAdapter.

Think of a dataset as a collection of tables and optionally information about the relationships between them.
In your example code you are creating an independent Table that does not belong to a DataSet. To pragmatically create a table that is part of a dataset you could do the following:
DataSet ds = new DataSet();
DataTable dt = ds.Tables.Add();
//or
ds.Tables.Add(MyAlreadyCreatedTable);
Jason Evans above is also correct, populating DataTables and DataSets is much simpler using SqlDataAdaptors as he demonstrated.
Finally, the Method as you have it written is meant to return a DataSet. But it only captures a single result set from the stored procedure it is calling. It's possible that a procedure could return any number of separate results.
All you should need to do is change the following:
DataTable table = new DataTable();
using (SqlDataReader reader = command.ExecuteReader())
{
table.Load(reader);
}
to
//you can skip creating a new DataTable object
using (SqlDataAdapter da = new SqlDataAdapter(command))
{
da.Fill(result); // the result set you created at the top
}

Which DataSet creation technique is faster?

Which one of these techniques is faster?
1)
DbDataAdapter dataAdapter = _factory.CreateDataAdapter();
dataAdapter.SelectCommand = _command;
dataSet = new DataSet();
dataAdapter.Fill(dataSet);
2)
DataTable dt = new DataTable();
IDataReader iDataReader= _command.ExecuteReader();
dt.Load(iDataReader);
iDataReader.Close();

Have a look at these links
DataReaders, DataSets, and performance
and
DataAdapter.Fill preferable to DataReader?
As mentioned in the comments to your question. It would be best to test for the given situation at hand, there is never a one rule applies to all.