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How to create a temporary table in MySql from C# datatable?

I am working on a project in which i get some data from a remote server and stores in datatable using C#
DataTable source_db_table;
public void fetch_from_source_db_table(bool verbose, string machine, string table_name, string time_from, string time_to)
{
string query =$"SELECT {table_name}.* " +
$"FROM {table_name} " +
$"WHERE {table_name}" +
$".u_time >='{time_from}' " +
$"AND u_time <= '{time_to}' " +
$"AND mac_id = '{machine}' OR mac_id = 0;";
source_db_table = select_db2(verbose, query);
now I want to use that "datatable" to create a temporary table in MySql . I have searched alot on internet but didnt find anything.

You can do something like this.
StringBuilder sCommand = new StringBuilder("create temporary table tablename(");
foreach (var Col in source_db_table .Columns)
{
sCommand.Append("`"+Col+"`" + " varchar(200), ");
}
sCommand.Append(");");
string scmd = ReplaceLastOccurrence(sCommand.ToString(), ",", "");
in this way your temporary table would be created and now you will just insert rows into this.

Use a database value to call a variable with the same name

I need to update a table called Calculated in my database, but because I have so many values that I have stored in my system as variables to add/update in the table, I created a separate table in the database called Database Relationships.
This Database Relationships table has a column called Calculated Value which holds all the field names of the Calculated table. The other column, System Field holds all the names of variables that I have created and given values to, which are of all string type and that relate to the corresponding Calculated Value
So by using a FOREACH loop
OleDbDataAdapter relationshipAdapter = new OleDbDataAdapter(relationshipCmd);
DataTable relationshipTable = new DataTable();
relationshipAdapter.Fill(relationshipTable);
string update = "Update [Calculated] SET ";
int i = 0;
int len = relationshipTable.Rows.Count;
foreach (DataRow drr in relationshipTable.Rows)
{
string calc = drr["Calculated Field"].ToString();
var sys = drr["System Field"].ToString();
if (i == len - 1)
{
update += "[" + calc + "] = " + sys + ";";
}
else
{
update += "[" + calc + "] = " + sys + ", ";
}
i++
}
update += "WHERE [NSN] = '" + NSN + "';";
OleDbCommand updateCmd = new OleDbCommand(update);
But this is not working, because after some debugging(?) I did a simple Console.WriteLine(sys) and it would print out the string in the System Field column, instead of the variable with the same name in the system.
I am currently using Microsoft Access as my database platform.

I think having "intermediate" table for temporary storing values in runtime for future saving in another table sounds little bid complicated for me.
If you want to map variables at runtime with column name in the database - use dictionary for example:
Dictionary<string, string> myValues = new Dictionary<string, string>();
Using in the application:
myValues["SomeColumn"] = "your value";
Then saving data to database will be:
var updateCmd = new OleDbCommand();
var query = new StringBuilder();
foreach(KeyValuePair<string, string> value in myValues)
{
string columnName = value.Key;
query.AppendLine($", {columnName} = ?");
var param = new OleDbParameter("#v", value.Value);
// Name of parameter not important, only order
}
if(query.Length > 0)
{
query.Remove(0, 1); // Remove first ',' character
query.Insert("Update [Calculated] SET ");
query.AppendLine("$WHERE [NSN] = '{NSN}';");
}
updateCmd.CommandText = query.ToString();
Very important: you need to use OleDbParameter for passing values to the query.

In you foreach loop, use this:
if (i == len - 1)
{
update += "[" + calc + "] = " + this.GetType().GetProperty(sys).GetValue(this, null)+ ";";
}
else
{
update += "[" + calc + "] = " + this.GetType().GetProperty(sys).GetValue(this, null)+ ", ";
}
The code above assumes that the variables are scoped in the same scope where you are generating your Sql.

In loop , you use the condition:
if (i == len - 1)
but you never change "len" or "i" value in the code.

Can't export large data from oracle to excel file using c#

I have a problem with extracting large data from oracle table to C#, and I
couldn't find the solution myself.
For this task I wrote a C# code, which loaded data from oracle procedure, which returns cursor, in excel file for the first time.
But when I tried to load bigger table (about 20 columns and 90 000 rows), it just didn't work.
Script doesn't fall with error, but data are not inserted into excel file.
I tried to load for 10 000 rows and then save the results, but again, only 30 000 rows were inserted.
I monitored the counter in loop, it is going correct and reach needed 90 000 and ExecuteNonQuery() always returned the value 10 000. But when I open excel file, there are only 30 000 rows there.
Can you please help me to catch the error, or may be somebody met the same problem, and can advise me what to do or what to read.
Thank you for any help!
I didn't write the connection string, but I think, it's correct, cause script works correctly with small datatable.
public static void Main()
{
string datetime = DateTime.Now.ToString("yyyy-MM-dd HH-mm-ss");
System.Threading.Thread.CurrentThread.CurrentUICulture = new System.Globalization.CultureInfo("en-US");
try
{
OleDbConnection Excel_OLE_Con = new OleDbConnection();
OleDbCommand Excel_OLE_Cmd = new OleDbCommand();
string qwe_constr = "connection string";
OracleConnection myADONETConnection = new OracleConnection(qwe_constr);
string connstring = "Provider=Microsoft.ACE.OLEDB.12.0;" + "Data Source=" + "E:\\qaz\\15.07.2016\\qwe" +
";" + "Extended Properties=\"Excel 12.0 Xml;HDR=YES;\"";
File.Delete("E:\\qaz\\15.07.2016\\qwe.xlsx");
//fill datatable with data for insert
myADONETConnection.Open();
OracleCommand cmd_proc = new OracleCommand();
cmd_proc.Connection = myADONETConnection;
cmd_proc.CommandType = System.Data.CommandType.StoredProcedure;
cmd_proc.CommandText = "procedure_name";
cmd_proc.Parameters.Add("p_show_del", OracleDbType.Int16).Value = 0;
cmd_proc.Parameters.Add("p_type", OracleDbType.Varchar2, 3).Value = "INV";
cmd_proc.Parameters.Add("p_errno", OracleDbType.Int16).Value = 157;
cmd_proc.Parameters.Add("outcur", OracleDbType.RefCursor).Direction = ParameterDirection.Output;
DataTable dt_with_data = new DataTable();
dt_with_data.Load(cmd_proc.ExecuteReader());
myADONETConnection.Close();
//string with column headers
string TableColumns = "";
foreach (DataColumn column in dt_with_data.Columns)
{
TableColumns += column + "],[";
}
// Replace most right comma from Columnlist
TableColumns = ("[" + TableColumns.Replace(",", " Text,").TrimEnd(','));
TableColumns = TableColumns.Remove(TableColumns.Length - 2);
//Use OLE DB Connection and Create Excel Sheet
Excel_OLE_Con.ConnectionString = connstring;
Excel_OLE_Con.Open();
Excel_OLE_Cmd.Connection = Excel_OLE_Con;
Excel_OLE_Cmd.CommandText = "Create table [sheet1] (" + TableColumns + ")";
Excel_OLE_Cmd.ExecuteNonQuery();
Excel_OLE_Con.Close();
//Write Data to Excel Sheet from DataTable dynamically
//string with command
Excel_OLE_Con.Open();
String sqlCommandInsert = "";
String sqlCommandValue = "";
foreach (DataColumn dataColumn in dt_with_data.Columns)
{
sqlCommandValue += dataColumn + "],[";
}
sqlCommandValue = "[" + sqlCommandValue.TrimEnd(',');
sqlCommandValue = sqlCommandValue.Remove(sqlCommandValue.Length - 2);
sqlCommandInsert = "INSERT into [sheet1] (" + sqlCommandValue + ") VALUES(";
int columnCount = dt_with_data.Columns.Count;
int i_qaz = 0;
foreach (DataRow row in dt_with_data.Rows)
{
i_qaz++;
Console.WriteLine(i_qaz.ToString());
string columnvalues = "";
for (int i = 0; i < columnCount; i++)
{
int index = dt_with_data.Rows.IndexOf(row);
columnvalues += "'" + dt_with_data.Rows[index].ItemArray[i].ToString().Replace("'", "''") + "',";
}
columnvalues = columnvalues.TrimEnd(',');
var command = sqlCommandInsert + columnvalues + ")";
Excel_OLE_Cmd.CommandText = command;
Excel_OLE_Cmd.ExecuteNonQuery();
}
}
catch (Exception exception)
{
// Create Log File for Errors
using (StreamWriter sw = File.CreateText("E:\\qaz\\15.07.2016\\qwe_" + datetime + ".log"))
{
sw.WriteLine(exception.ToString());
}
}
}
PS: Same question in Russian.

How to present the data from multiple DataTables in a series of stacked data grids?

I have an undefined amount of DataTables. I get them from my DataBase, each DataTable stands for one Table in my DataBase, I dont use all Tables of the DataBase just the few I need (these were selectet earlier in the code) and not all columns (same like the tables).
Now my problem: I want to show them in a DataGrid one below the other with breaks between them for the tablename.
This is how i get my DataTables:
List<DBTable> selectedTbl = DBObject.SingDBObj.GetSelectedTables();
foreach (DBTable tbl in selectedTbl)
{
string cols = tbl.GetSelectedColumnNames();
string query = #"SELECT " + cols + " FROM [" + DBObject.SingDBObj.DataSource + "].[" + DBObject.SingDBObj.Database + "].[" + tbl.Schema + "].[" + tbl.Name + "];";
DataTable DTShow = DBObject.SingDBObj.ExecuteQuery(query);
}
dataGridShowColmns.DataContext = ??;
Is there an easy way to do this?

You maybe mean something like:
DataSet ds = new DataSet();
// dataset is here just initialized for demonstration, you would first
// get the tables from database and populate dataset
for (int i = 0; i < ds.Tables.Count; i++)
{
DataTable dt = ds.Tables[i];
foreach (DataRow dr in dt.Rows)
{
dataGridView1.Rows.Add(dr);
}
}

In SQL name to a dataset cannot be assigned, only way you can do it in c#/VB. like
Dataset.Table[0].Name = "MyTable";

How to import Excel Document Data, Sheet by Sheet, into SQL tables

I need to import data from an excel file into my SQL Server Database. The datafile contains about 120,000 records(rows) that I need to import. Each row of data in the excel file consists of about 183 formatted columns of data, and the data is to be dispersed to about 13 different tables on the SQL end. What would be the best way(easiest but high performance) to import all those records to the SQL, making sure that each row is properly processed.
Another option is to have an option that loads the data into a temp data table in a Database, and then run the script to move all columns of data from the temp table into the various other tables.

I use this way to get data from CSV file :->
int f = 0;
var reader = new StreamReader(File.OpenRead(#ExcelFilePath));
Buisness_logic bl = new Buisness_logic();
while (!reader.EndOfStream)
{
if (f == 0)
{
var line = reader.ReadLine();
f++;
}
else
{
var line = reader.ReadLine();
string[] s = line.Split(',');
count = s.Length;
if (s.Length == 3)
{
var values = line.Split(',');
string query = "Insert into Events_party values('" + identity + "','" + values[0] + "','" + values[1] + "','" + values[2] + "','" + time + "','" + dt + "')";
bl.ExecuteQuery(query);
count = 101;
}
else
{
MessageBox.Show("Imported File was not in defined format !! ", ".File Format Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
textBox1.BackColor = Color.Pink;
break;
count = 100;
}
}
}