Develop Reference

Make Data columns from a sql adapter

Is there a way, where I can use a sql adapter and convert the sql query results into a Data Columns? I'm kinda new a datatables. I need to build this dynamically since my column names are stored into a sql table. I keep running into datarows not columns. What I have built so far:
string feedcolumns = #"select FeedColumnName from myTable where FeedProcessID = #feedprocessid";
SqlCommand columnscommand = new SqlCommand(feedcolumns, connUpd);
DataTable dt = new DataTable("datafeed");
foreach(DataColumn dc in dt.Columns)
{
dc = new
dt.Columns.Add(dc);
}

You can fill a DataTable directly from an SqlReader, no need to go column by column.
One thing I did notice was that your SQL statement had a parameter in it that was never assigned to the command object, so I added it in
string feedcolumns = "select FeedColumnName from myTable where FeedProcessID = #feedprocessid";
DataTable dt = new DataTable("datafeed");
using (SqlConnection connUpd = new SqlConnection("MyConnection")) {
using (SqlCommand columnscommand = new SqlCommand(feedcolumns, connUpd)) {
columnscommand.Parameters.AddWithValue("#feedprocessid", feedprocessid);
connUpd.Open();
var dataReader = columnscommand.ExecuteReader();
dt.Load(dataReader);
}
}

Get distinct values from column by column

Have to get each columns distinct data and store to the Dictionary (or array) using Excel.interop. I have tried the following code, but it does not align with Excel.interop.
var excel = new ExcelQueryFactory("worksheetFileName");
var distinctNames = (from row in excel.WorkSheet() select row["ColB"]).Distinct();
Please provide the Excel.Interop snippet/code to get distinct values column by column and store in array.

For this operation it does not make sense to using Excel automation, instead the prudent course of action is to work with OleDb unless there is a sound reason for using Excel automation.
Example, figure 1 is a function to create a connection string which can be used in any project while figure 2 is for reading data.
To work with Excel automation we open ourselves up to objects not being disposed of if there is a crash or that you do not code properly (this I call the two dot rule) when objects can't be released because of how you created and used automation objects which does not happen with OleDb. Now if you wanted formatting than we move to automation.
public string ConnectionString(string FileName, string Header)
{
OleDbConnectionStringBuilder Builder = new OleDbConnectionStringBuilder();
if (System.IO.Path.GetExtension(FileName).ToUpper() == ".XLS")
{
Builder.Provider = "Microsoft.Jet.OLEDB.4.0";
Builder.Add("Extended Properties", string.Format("Excel 8.0;IMEX=1;HDR={0};", Header));
}
else
{
Builder.Provider = "Microsoft.ACE.OLEDB.12.0";
Builder.Add("Extended Properties", string.Format("Excel 12.0;IMEX=1;HDR={0};", Header));
}
Builder.DataSource = FileName;
return Builder.ConnectionString;
}
Code to read the first column in Sheet2 and get distinct values, in this case I am working against a column with dates as string into List where the file resides in the same folder as the app executable
private List<string> DemoDistinct()
{
List<string> dateList = new List<string>();
DataTable dt = new DataTable();
using (OleDbConnection cn = new OleDbConnection { ConnectionString = ConnectionString(System.IO.Path.Combine(Application.StartupPath, "WS1.xlsx"), "Yes") })
{
cn.Open();
using (OleDbCommand cmd = new OleDbCommand
{
CommandText = "SELECT DISTINCT [Dates] FROM [Sheet2$]",
Connection = cn
}
)
{
OleDbDataReader dr = cmd.ExecuteReader();
dt.Load(dr);
dateList = dt
.AsEnumerable()
.Select(row => row.Field<DateTime>("Dates").ToShortDateString()).ToList();
}
}
return dateList;
}

C# sql IF NOT EXIST statement not working?

Not sure if this is written correctly but it looks correct. I am wanting to update a record if the id already exists and insert if not.
DataSet ds = new DataSet();
ds.ReadXml(XDocument.Load(Application.StartupPath + #"\xml1.xml").CreateReader());
using (var conn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" + Application.StartupPath + "\\Database3.mdb"))
{
conn.Open();
// make two commands here
var commInsert = new OleDbCommand("Insert INTO Table1 (description, active) VALUES (#iq_question,#active);", conn);
var commUpdate = new OleDbCommand("UPDATE Table1 SET description=#iq_question,active=#active WHERE ID=#question_id;", conn);
// here add your parameters with no value
//string question_id = row[0].ToString();
//string iq_question = row[1].ToString();
//string active = row[4].ToString();
commInsert.Parameters.Add(new OleDbParameter("#iq_question", OleDbType.VarChar));
commInsert.Parameters.Add(new OleDbParameter("#active", OleDbType.VarChar));
commUpdate.Parameters.Add(new OleDbParameter("#question_id", OleDbType.AutoNumber));
commUpdate.Parameters.Add(new OleDbParameter("#iq_question", OleDbType.Text));
commUpdate.Parameters.Add(new OleDbParameter("#active", OleDbType.Text));
foreach (DataTable table in ds.Tables)
{
foreach (DataRow row in table.Rows)
{
// here only reset the values
commUpdate.Parameters["#question_id"].Value = row[0].ToString();
commUpdate.Parameters["#iq_question"].Value = row[1].ToString();
commUpdate.Parameters["#active"].Value = row[4].ToString();
int recs = commUpdate.ExecuteNonQuery();
if (recs < 1) // when no records updated do insert
{
commInsert.Parameters["#iq_question"].Value = row[1].ToString();
commInsert.Parameters["#active"].Value = row[4].ToString();
commInsert.ExecuteNonQuery();
}
}
}
commInsert.Dispose();
commUpdate.Dispose();
conn.Close();
}
System.Windows.Forms.MessageBox.Show("Updated Latest Data Was Succesfull");
I either get an error on the insert saying it will create duplicate content, or it creates more rows with different data. So say I should be getting 10 rows from the xml file, the first time I run it I get the 10 rows with the correct data. If I run it again, I end up with 10 more so being 20 but the last 10 rows show different data. I don't think I am identifying the rows in the xml file correctly and I need to do some research on that part.

There is no Exists for MS Access. The engine is much more primitive than Sql Server. See here: Microsoft Access SQL. I think, what you can do is:
myCommand.CommandText = "UPDATE Table1 SET description=#iq_question,active=#active WHERE ID=#currentRow";
......
int recs = myCommand.ExecuteNonQuery();
if (recs < 1) // when no records updated do insert
{
myCommand.Parameters.Clear();
myCommand.CommandText = "Insert INTO Table1 VALUES(#iq_question,#active)";
.....
}
This is still 2 statements but you can save some coding by not doing Select first. Because ExecuteNonQuery will tell you if you updated anything
Another thing is that your code is a bit inefficient. You have nested loop where you can reuse same command and connection. Yuu can do this
using (var conn = new OleDbConnection(.......))
{
conn.Open();
// make two commands here
var commInsert = new OleDbCommand(.....);
var commUpdate = new OleDbCommand(.....);
// here add your parameters with no value
commInsert.Parameters.Add(new OleDbParameter(....));
.......
Foreach (....)
{
Foreach (....)
{
// here only reset the values
commUpdate.Parameters[0].Value = ...
...
int recs = commUpdate.ExecuteNonQuery();
if (recs < 1) // when no records updated do insert
{
commInsert.Parameters[0].Value = iq_question;
.....
}
}
}
commInsert.Dispose();
commUpdate.Dispose();
}
You can also use nested using for commands. Only setting values will be more efficient to what you do right now.

How to insert multiple list in SQL Server 2008 using c#?

My table contains 10 columns. I need to insert a list using c#.
I have stored the details of multiple members, for each count its has to insert the consecutive details in the same row.
if (members.Count >= 1)
{
foreach (Members myList in members)
{
Command.Parameters.Add("first", SqlDbType.VarChar).Value = myList.first;
Command.Parameters.Add("last", SqlDbType.VarChar).Value = myList.last;
Command.Parameters.Add("age", SqlDbType.VarChar).Value = myList.age;
}
}
Example : for count=1 the table looks like
"fName1","lName1",21
for count=2 the table looks like
"fName1","lName1",21,"fname2","lName2",21
please help on this.

The coding style looks ambiguous. Your foreach loop runs for - 'Members' in members. It makes hard to understand what are trying to do. Let me suggest you to refactor your code and let the class name be 'Member'. You can put members in db with ADO.Net (there are other ways too) as follows -
using (SqlConnection connection = new SqlConnection(connectionString))
{
using (SqlCommand command = connection.CreateCommand())
{
//select just schema of the table.
command.CommandText = "select * from members where 1=2;";
using (SqlDataAdapter adapter = new SqlDataAdapter(command))
{
using (SqlCommandBuilder builder = new SqlCommandBuilder(adapter))
{
using (DataTable dt = new DataTable())
{
foreach (Member item in memebers)
{
DataRow row = dt.NewRow();
row.SetField<string>("", item.FirstName);
row.SetField<string>("", item.LastName);
row.SetField<int>("", item.Age);
//
// number of SetField should be equal to number of selected columns.
//
dt.Rows.Add(row);
}
adapter.Update(dt);
}
}
}
}
}

Skip some columns in SqlBulkCopy

I'm using SqlBulkCopy against two SQL Server 2008 with different sets of columns (going to move some data from prod server to dev). So want to skip some columns not yet existed / not yet removed.
How can I do that? Some trick with ColumnMappings?
Edit:
I do next:
DataTable table = new DataTable();
using (var adapter = new SqlDataAdapter(sourceCommand))
{
adapter.Fill(table);
}
table.Columns
.OfType<DataColumn>()
.ForEach(c => bulk.ColumnMappings.Add(
new SqlBulkCopyColumnMapping(c.ColumnName, c.ColumnName)));
bulk.WriteToServer(table)
and get:
The given ColumnMapping does not match up with any column in the source or destination.

DataTable table = new DataTable();
using (var adapter = new SqlDataAdapter(sourceCommand))
{
adapter.Fill(table);
}
using (SqlBulkCopy bulk = new SqlBulkCopy(targetConnection, SqlBulkCopyOptions.KeepIdentity, null) { DestinationTableName = tableName })
{
foreach (string columnName in GetMapping(stringSource, stringTarget, tableName))
{
bulk.ColumnMappings.Add(new SqlBulkCopyColumnMapping(columnName, columnName));
}
targetConnection.Open();
bulk.WriteToServer(table);
}
private static IEnumerable<string> GetMapping(string stringSource, string stringTarget, string tableName)
{
return Enumerable.Intersect(
GetSchema(stringSource, tableName),
GetSchema(stringTarget, tableName),
StringComparer.Ordinal); // or StringComparer.OrdinalIgnoreCase
}
private static IEnumerable<string> GetSchema(string connectionString, string tableName)
{
using (SqlConnection connection = new SqlConnection(connectionString))
using (SqlCommand command = connection.CreateCommand())
{
command.CommandText = "sp_Columns";
command.CommandType = CommandType.StoredProcedure;
command.Parameters.Add("#table_name", SqlDbType.NVarChar, 384).Value = tableName;
connection.Open();
using (var reader = command.ExecuteReader())
{
while (reader.Read())
{
yield return (string)reader["column_name"];
}
}
}
}

When SqlBulkCopyColumnMapping is used, only columns for which mappings are created will be copied.
If you do not create a mapping for a column, it will be ignored by the copy process.
You can see this in the demo code here - the sample source table in the AdventureWorks demo database contains more columns than are mapped or copied.
EDIT
It's difficult to be certain without more information about the database schema, but at a guess the issue is with this statement:
new SqlBulkCopyColumnMapping(c.ColumnName, c.ColumnName)
From your description, it sounds like not all the columns in the source table exist in the destination table. You need a filter in your SqlBulkCopyColumnMapping construction loop to skip any columns which do not exist in the destination.
My C# is not good enough to give a example which I'm confident will work, but in pseudocode it would be
foreach column c in sourcetable
{
if c.ColumnName exists in destination_table.columns
{
new SqlBulkCopyColumnMapping(c.ColumnName, c.ColumnName)
}
}
(I'm sure it's possible to convert this to a lambda expression)
Note that this is not particularly robust in the scenario where the column names match but the datatypes are incompatible.

Ed Harper, this is what it looks like without pseudo code
(in this case from DataTable dt (fully defined) to an existing table in the db:
using (SqlBulkCopy bulkCopy = new SqlBulkCopy(connectionString))
{
bulkCopy.DestinationTableName = "dbo.DepartmentsItems";
// Write from the source to the destination.
foreach (DataColumn c in dt.Columns)
{
bulkCopy.ColumnMappings.Add(c.ColumnName, c.ColumnName);
}
bulkCopy.WriteToServer(dt);
return dt.Rows.Count;
}

try this:SqlBulkCopyColumnMapping Class
Hope you are looking for the same