Develop Reference

Bulk Update in SQL Server from C#

I have to update multiple records in SQL Server table from C#. Below are the steps I have to follow and below is the code.
The code is working but the process is taking much longer than expected.
I need a quick way to update 10000 records, not sure whether Bulk Copy would work for Update.
I have seen the other answers which has Bulk insert to temp and then update..But that update has a single statement and here I need to update the records in DB based on Excel data and for this I have to loop each excel record.So how can I achieve faster update.
1) Read the Excel Data and copied the data into a data table
string strDirectory = string. Empty;
strDirectory = System.IO.Directory.GetCurrentDirectory() + "\\" + "Filename.xlsx";
string Connection String = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source = " + strDirectory + "; Extended Properties = \"Excel 12.0;HDR=YES;IMEX=1\"";
using (OleDbConnection conn = new OleDbConnection(Connection String))
{
conn.Open();
DataTable schemaTable = conn.GetOleDbSchemaTableOleDbSchemaGuid.Tables, new object[] { null, null, null, "TABLE" });
DataRow schemaRow = schemaTable. Rows[0];
string sheet = schemaRow["TABLE_NAME"].ToString();
string query = "SELECT * FROM [" + sheet + "]";
OleDbDataAdapter daexcel = new OleDbDataAdapter(query, conn);
daexcel.Fill(dt);
conn.Close();
}
2) Doing some manipulations on datatable data before updating into table.
string strsqlst = string. Empty;
using (SqlConnection sqlConn = new SqlConnection(Connectionstring))
{
sqlConn.Open();
SqlCommand cmd;
StringBuilder sb = new StringBuilder();
sb.AppendLine("DataTable content:");
foreach (DataRow row in dt.Rows)
{
if (row.ItemArray[0].ToString() == "")
break;
strsqlst = "Update table Set col1= " + row.ItemArray[4].ToString() + " ,col2= " + row.ItemArray[5].ToString() + " where <Condition>'";
cmd = new SqlCommand(strsqlst, sqlConn);
cmd.CommandType = CommandType.Text;
cmd.ExecuteNonQuery();
}
sqlConn.Close();
}

The SqlCommand can be a whole SQL batch and is not limited to a single statement. So you can create a single large batch with 10,000 UPDATE statements, or divide it into for example 20 batches of 500 each.
In other words, you can create a single command with CommandText like this:
UPDATE [T] SET Col1='Value1', Col2='Value2' WHERE [Id] = 1;
...
UPDATE [T] SET Col1='Value999', Col2='Value1000' WHERE [Id] = 500;
That said, you should use parameters for all data values (to ensure SQL injection is not possible).
If you want to handle any errors (updates failing due to invalid data) you will need something a bit more sophisticated.

How to retrieve data from database based on selected value in combo box?

Im new to c# here. I have a comboBox codes that enable user to choose month and dates. When user click cmdSend button, the program will retrieve the month & date form comboBox and call dbConnect.Select class function to do the select mysql statement.
private void cmdSend_Click(object sender, System.EventArgs e)
{
List<string>[] list;
list = dbConnect.Select(month_list.Text, year_list.Text);
printer_info.Rows.Clear();
for (int i = 0; i < list[0].Count; i++)
{
int number = printer_info.Rows.Add();
printer_info.Rows[number].Cells[0].Value = list[0][i];
printer_info.Rows[number].Cells[1].Value = list[1][i];
printer_info.Rows[number].Cells[2].Value = list[2][i];
printer_info.Rows[number].Cells[3].Value = list[3][i];
}
}
the retrieve database class:
public List<string>[] Select(string month,string year)
{
string query = "SELECT * FROM page_counter where month ='" + month + "' AND year ='" + year + "' ;";
//Create a list to store the result
List<string>[] list = new List<string>[4];
list[0] = new List<string>();
list[1] = new List<string>();
list[2] = new List<string>();
list[3] = new List<string>();
//Open connection
if (this.OpenConnection() == true)
{
//Create Command
MySqlCommand cmd = new MySqlCommand(query, connection);
//Create a data reader and Execute the command
MySqlDataReader dataReader = cmd.ExecuteReader();
//Read the data and store them in the list
while (dataReader.Read())
{
list[0].Add(dataReader["id"].ToString() + "");
list[1].Add(dataReader["month"].ToString() + "");
list[2].Add(dataReader["year"].ToString() + "");
list[3].Add(dataReader["page_count"].ToString() + "");
}
//close Data Reader
dataReader.Close();
//close Connection
this.CloseConnection();
//return list to be displayed
return list;
}
else
{
return list;
}
}
However this code does not work, can someone advise me please?
EDITED:
string query = "SELECT * FROM page_counter where month = #month AND year = #year;";
//Open connection
if (this.OpenConnection() == true)
{
//Create Command
MySqlCommand cmd = new MySqlCommand(query, connection);
cmd.Parameters.AddWithValue("#month",month);
cmd.Parameters.AddWithValue("#year",year );
//Create a data reader and Execute the command
MySqlDataReader dataReader = cmd.ExecuteReader();
//Read the data and store them in the list
while (dataReader.Read())
{
list[0].Add(dataReader["id"].ToString() + "");
list[1].Add(dataReader["month"].ToString() + "");
list[2].Add(dataReader["year"].ToString() + "");
list[3].Add(dataReader["page_count"].ToString() + "");
}
//close Data Reader
dataReader.Close();
I have edited the code as suggested,However I have an error on the AddWithValue, it say : does not contain a definition for AddWithValue and no extension method AddWithValue, I have added the Data.MySqlClient reference but still remain the same. Please advise.

Problem 1 : You need to use SelectedItem property of the combobox to get the selected item from it.
Solution 1:
Replace This:
list = dbConnect.Select(month_list.Text, year_list.Text);
With This:
list = dbConnect.Select(month_list.SelectedItem.ToString(),
year_list.SelectedItem.ToString());
Problem 2:
i beilve that your Month and Year columns in your Database are INT columns.if they are INT columns you dont need to enclose the month and year parameter values within single quotes.
Solution 2:
Try This:
string query = "SELECT * FROM page_counter where month =
" + month + " AND year =" + year + " ;";
Suggestion : Your query is open to sql injection attacks i'd suggest to use Parameterised queries to avoid them.
Try This with Parameterised queries:
string query = "SELECT * FROM page_counter where month = #month AND year = #year;";
//Open connection
if (this.OpenConnection() == true)
{
//Create Command
MySqlCommand cmd = new MySqlCommand(query, connection);
cmd.Parameters.AddWithValue("#month",month);
cmd.Parameters.AddWithValue("#year",year );
//Remaining same
//Create a data reader and Execute the command
MySqlDataReader dataReader = cmd.ExecuteReader();
//Read the data and store them in the list
while (dataReader.Read())
{
list[0].Add(dataReader["id"].ToString() + "");
list[1].Add(dataReader["month"].ToString() + "");
list[2].Add(dataReader["year"].ToString() + "");
list[3].Add(dataReader["page_count"].ToString() + "");
}
//close Data Reader
dataReader.Close();

C# and SQLCE Database Not Updating

Ok, I have been having a problem the last few days with my database not updating. I can read the data fine and I'm not getting any exceptions either. I'm trying to update the database then I try to read values again after the update (during same run), and they still hold the original values, so it doesn't seem to be an issue with the database being copied to another folder (I'm using Copy if newer yet neither database is being updated).
Here is the code I'm using. As you can see I tried a few different approaches, none of which worked yet.
public void UpdateDatabaseInStock(string itemName, string tableName)
{
DataSet data = new DataSet("Items");
int val;
//get the file path to the database as a string
string dbfile =
new System.IO.FileInfo(System.Reflection.Assembly.GetExecutingAssembly().Location).DirectoryName +
"\\Database\\GameData.sdf";
//connect to the database
using (SqlCeConnection cntn = new SqlCeConnection("datasource=" + dbfile))
{
//create an adapter to pull all data from the table
using (SqlCeDataAdapter adpt = new SqlCeDataAdapter
("SELECT * FROM " + tableName + " WHERE Name LIKE '%" + itemName + "%'", cntn))
{
//put the data into a DataSet
adpt.Fill(data);
cntn.Close();
}
//fill the data from the Items table into a DataTable to return.
DataTable itemTable = data.Tables[0];
DataRow a = itemTable.Rows[0];
val = (short)a.ItemArray[3] - 1;
dbfile = "";
data.Dispose();
itemTable.Dispose();
SqlCeCommand cmd = new SqlCeCommand();
cmd.Connection = cntn;
cntn.Open();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "UPDATE " + tableName + " SET [In Stock] = #Value WHERE [Name] = '#ItemName'";
//cmd.Parameters.Add("#Value", SqlDbType.SmallInt);
//cmd.Parameters["#Value"].Value = val;
//cmd.Parameters.Add("#ItemName", SqlDbType.NChar, 75);
//cmd.Parameters["#ItemName"].Value = itemName;
cmd.Parameters.AddWithValue("#Value", val);
cmd.Parameters.AddWithValue("#ItemName", itemName);
cmd.ExecuteNonQuery();
//close the conenction
cntn.Close();
cmd.Dispose();
}
}
Any ideas to get it to actually update?

Just a hunch (can't corroborate this on msdn): could it be that using nchar(75) adds spaces to the parameter, thereby causing the WHERE clause to fail?

how to reference columns in sql server connection in C#

I'm trying to translate some perl code into C# and I'm having some trouble with the following.
After establishing a sql server connection and executing the select statement, how do I reference the different elements in the table columns. For example, in Perl it looks like:
my $dbh = DBI -> connect( NAME, USR, PWD )
or die "Failed to connect to database: " . DBI->message;
my $dbname = DB_NAME;
my $dbschema = DB_SCHEMA;
my $sql = qq{select a,b,c,d,e,f,g,h,i,...
from $dbname.$dbschema.package p
join $dbname.$dbschema.package_download pd on p.package_id = pd.package_id
join $dbname.$dbschema.download d on pd.download_id = d.download_id
where p.package_name = '$package'
--and ds.server_address like 'tcp/ip'
order by a,b,c,d,..};
my $sth = $dbh -> prepare( $sql )
or die "Failed to prepare statement: " . $dbh->message;
$sth -> execute()
or die "Failed to execute statement: " . $sth->message;
#now to go through each row in result table
while ( #data = $sth->fetchrow_array() )
{
print "$data[0]";
# If source server FTP is not already open, make new FTP
if ( $data[0] != $src_id )
{
if ( $src_ftp )
{ $src_ftp -> quit; }
$src_ftp = make_ftp( $data[1], $data[2], $data[3], $data[18], $data[19], $data[20] );
$src_id = $data[0];
}
}
so far I've got it down to
string db = NAME;
string myConnectionString = "Data Source=ServerName;" + "Initial Catalog=" + db + "User id=" + ODBC_USR + "Password=" + PWD
SqlConnection myConnection = new SqlConnection(myConnectionString);
string myInsertQuery = "select a,b,c,d,e,f,g,h,i,...
from $dbname.$dbschema.package p
join $dbname.$dbschema.package_download pd on p.package_id = pd.package_id
join $dbname.$dbschema.download d on pd.download_id = d.download_id
where p.package_name = '$package'
--and ds.server_address like 'tcp/ip'
order by a,b,c,d,..";
SqlCommand myCommand = new SqlCommand(myInsertQuery);
myCommand.Connection = myConnection;
myConnection.Open();
myCommand.ExecuteNonQuery();
myCommand.Connection.Close();
but how do I reference the columns like data[0] and data[1] in C#. Sorry I'm new to both languages so my background is severely lacking. Thanks!

You could reference your column directly by its column name or by numeric order (it starts with 0 as the first column) either through a DataTable, DataSet, DataReader or a specific DataRow.
For the sake of example i'll use a DataTable here and I will name it as dt and let's say we want to reference the first row then you could reference it with the following Syntax/Format:
dt[RowNumber]["ColumnName or Column Number"].ToString();
For example:
dt[0]["a"].ToString();
Or by number the first column with be 0 like:
dt[0][0].ToString();
And use Parameters by the way because without which it would be susceptible to SQL Injection. Here's a more complete code below:
string db = NAME;
string myConnectionString = "Data Source=ServerName;" + "Initial Catalog=" + db + "User id=" + ODBC_USR + "Password=" + PWD
using (SqlConnection connection = new SqlConnection(myConnectionString))
{
string mySelectQuery = #"SELECT a,b,c,d,e,f,g,h,i,...
FROM package p
JOIN package_download pd on p.package_id = pd.package_id
join download d on pd.download_id = d.download_id
WHERE p.package_name = #PackageName
AND ds.server_address LIKE 'tcp/ip%'
ORDER by a,b,c,d";
try
{
connection.Open();
using (SqlDataAdapter da = new SqlDataAdapter(mySelectQuery, connection))
{
using (SqlCommand cmd = new SqlCommand())
{
da.SelectCommand.Parameters.AddWithValue("#PackageName", txtPackage.Text);
DataTable dt = new DataTable();
da.Fill(dt);
if (dt.Rows.Count>0) // Make sure there is something in your DataTable
{
String aVal = dt[0]["a"].ToString();
String bVal = dt[0]["b"].ToString();
// You'll be the one to fill up
}
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
I change your LIKE 'tcp/ip' to LIKE 'tcp/ip%' by the way which is the more appropriate one of using LIKE.

you can use ado.net entity data table to reference the tables in your sql server. I don't know if you're asking exactly this but it may help. because direct referencing to sql server is not possible as far as i know.

How to retrieve all fields for a given record using OracleDataReader?

My question, which is similar to this one, is how can I use OracleDataReader to retrieve all the fields for a given record? Currently, I've been using this method, which returns only one column value at a time:
public string Select_File(string filename, string subdirectory, string envID)
{
Data_Access da = new Data_Access();
OracleConnection conn = da.openDB();
OracleCommand cmd = new OracleCommand();
cmd.Connection = conn;
cmd.CommandText = "SELECT * FROM EIP_Deployment_Files"
+ " WHERE Filename ='" + filename + "'"
+ " AND Subdirectory = '" + subdirectory + "'"
+ " AND Environment_ID = '" + envID + "'";
cmd.CommandType = CommandType.Text;
string x;
OracleDataReader dr = cmd.ExecuteReader();
if (dr.HasRows) // file exists in DB
{
dr.Read();
x = dr.GetString(2).ToString(); // return baseline filename (index 2)
}
else
{
x = "New File";
}
cmd.Dispose();
da.CloseDB(conn);
return x;
}
I'm sure that this method is far from perfect and ppl will be quick to point that out (I was basically given it by my supervisor since I didn't have any prior experience in ASP.NET) but all I really care about is that it works. My question is: how can it be modified to return all the fields for a given record?
The fields will be of either VARCHAR2, CHAR, or DATE datatypes, (if that makes a difference) and some of these values may be null. I'm thinking I could convert them to strings and return them as a list?

if u want something like this:
List<User> lstUser = new List<User>();
string sqlQuery = "Select * from User_T where User_Name='" + oUser.UserName + "' And Password='" +oUser.Password + "' AND IsActive='"+1+"' AND IsDelete='"+0+"'";
string connectionString = "Data Source=ORCL;User Id=ACCOUNTS;Password=ACCOUNTS";
using (DBManager dbManager = new DBManager(connectionString))
{
try
{
dbManager.Open();
OracleDataReader dataReader = dbManager.ExecuteDataReader(sqlQuery);
while (dataReader.Read())
{
oUser = new User();
oUser.Id = Convert.ToInt32(dataReader["ID"]);
oUser.CompanyId = Convert.ToInt32(dataReader["Company_ID"]);
oUser.BranchId = Convert.ToInt32(dataReader["Branch_ID"]);
oUser.UserName = Convert.ToString(dataReader["User_Name"]);
lstUser.Add(oUser);
}
dataReader.Close();
dataReader.Dispose();
}
catch
(Exception)
{
}
finally
{
dbManager.Close();
dbManager.Dispose();
}

To read all the data from the columns of the current row in a DataReader, you can simply use GetValues(), and extract the values from the array - they will be Objects, of database types.
Object[] values;
int numColumns = dr.GetValues(values); //after "reading" a row
for (int i = 0; i < numColumns; i++) {
//read values[i]
}
MSDN - "For most applications, the GetValues method provides an efficient means for retrieving all columns, rather than retrieving each column individually."

Sorry for posting an answer to a very old question. As none of the answers are correct (either they have security issues or not checking for DBNull), I have decided to post my own.
public async Task<StringBuilder> FetchFileDetailsAsync(string filename, string subdirectory, string envId)
{
var sb = new StringBuilder();
//TODO: Check the parameters
const string connectionString = "user id=userid;password=secret;data source=" +
"(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=10.0.0.8)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=xe)))";
const string selectQuery = "SELECT * FROM EIP_Deployment_Files"
+ " WHERE Filename = :filename"
+ " AND Subdirectory = :subdirectory"
+ " AND Environment_ID = :envID"
+ " AND rownum<=1";
using (var connection = new OracleConnection(connectionString))
using (var cmd = new OracleCommand(selectQuery, connection) {BindByName = true, FetchSize = 1 /*As we are expecting only one record*/})
{
cmd.Parameters.Add(":filename", OracleDbType.Varchar2).Value = filename;
cmd.Parameters.Add(":subdirectory", OracleDbType.Varchar2).Value = subdirectory;
cmd.Parameters.Add(":envID", OracleDbType.Varchar2).Value = envId;
//TODO: Add Exception Handling
await connection.OpenAsync();
var dataReader = await cmd.ExecuteReaderAsync(CommandBehavior.CloseConnection);
var rowValues = new object[dataReader.FieldCount];
if (dataReader.Read())
{
dataReader.GetValues(rowValues);
for (var keyValueCounter = 0; keyValueCounter < rowValues.Length; keyValueCounter++)
{
sb.AppendFormat("{0}:{1}", dataReader.GetName(keyValueCounter),
rowValues[keyValueCounter] is DBNull ? string.Empty : rowValues[keyValueCounter])
.AppendLine();
}
}
else
{
//No records found, do something here
}
dataReader.Close();
dataReader.Dispose();
}
return sb;
}