How to get numbers of rows in sql query? - c#

string query = q;
SqlCommand queryCommand = new SqlCommand(query, Connection);
SqlDataReader queryCommandReader = queryCommand.ExecuteReader();
DataTable dataTable = new DataTable();
dataTable.Load(queryCommandReader);
List<string> rowText = new List<string>();
for (int i = 0; i < 4; i++)
{
foreach (DataColumn columns in dataTable.Columns)
{
rowText.Add(dataTable.Rows[i][columns.ColumnName] + "");
}
}
in this example I get 4 rows from database the condition in for loop i < 4
I wanna get really numbers of rows not just 4


Use foreach for the rows as well
See http://msdn.microsoft.com/en-us/library/system.data.datatable.rows.aspx
foreach(DataRow row in dataTable.Rows)
{
foreach (DataColumn column in dataTable.Columns)
{
rowText.Add( row[column] );
}
}


In your specific example simple replace the the 4 by dataTable.Rows.Count so that you get:
for(int i = 0; i < dataTable.Rows.Count; i++)
{
// ...
}
Or switch to foreach and use the answer of Gaby.

Related

How to compare 2 dataTable in c#

How can I compare the 2 dataTable in c#
For example
dataTable1
a,a,a,a,1,a,a,a,a,a
a,a,a,a,1,a,a,a,a,a
a,a,a,a,2,a,a,a,a,a
a,a,a,a,2,a,a,a,a,a
a,a,a,a,3,a,a,a,a,a
dataTable2
b,b,b,b,1,b,b,b,b,b
b,b,b,b,1,b,b,b,b,b
b,b,b,b,1,b,b,b,b,b
b,b,b,b,2,b,b,b,b,b
b,b,b,b,2,b,b,b,b,b
How do I run the 1st row in dataTable1 [5] which is = 1, if dataTable2 [5] also consists 1 then print out the line. Continue until finish. Then Continue loop to second one in dataTable1 check with dataTable2
Here is my code
using System;
using System.Collections.Generic;
using System.Data;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace CompareLinuxWithWindow
{
class Program
{
static void Main(string[] args)
{
DataTable dt1 = ConvertToDataTable(#"C:\Users\manchunl\Desktop\Sample1.txt", 10);
DataTable dt2 = ConvertToDataTable2(#"C:\Users\manchunl\Desktop\Sample2.txt", 10);
foreach (DataRow row in dt1.AsEnumerable())
{
string temp_dt1 = "";
string[] words = temp_dt1.Split(',');
string.Join(",", row.ItemArray.Select(x => x.ToString()));
temp_Linux = (string.Join(",", row.ItemArray.Select(x => x.ToString())));
}
foreach (DataRow row in dt2.AsEnumerable())
{
string temp_dt2 = "";
string.Join(",", row.ItemArray.Select(x => x.ToString()));
temp_dt2 = (string.Join(",", row.ItemArray.Select(x => x.ToString())));
}
Console.WriteLine();
Console.WriteLine("Press enter to exit.");
Console.Read();
}
public static DataTable ConvertToDataTable(string filePath, int numberOfColumns)
{
DataTable tbl = new DataTable();
for (int col = 0; col < numberOfColumns; col++)
tbl.Columns.Add(new DataColumn("Column" + (col + 1).ToString()));
string[] lines = System.IO.File.ReadAllLines(filePath);
foreach (string line in lines)
{
var cols = line.Split(null);
DataRow dr = tbl.NewRow();
for (int cIndex = 0; cIndex < numberOfColumns; cIndex++)
{
dr[cIndex] = cols[cIndex];
}
tbl.Rows.Add(dr);
}
return tbl;
}
public static DataTable ConvertToDataTable2(string filePath, int numberOfColumns)
{
DataTable tbl = new DataTable();
for (int col = 0; col < numberOfColumns; col++)
tbl.Columns.Add(new DataColumn("Column" + (col + 1).ToString()));
string[] lines = System.IO.File.ReadAllLines(filePath);
foreach (string line in lines)
{
var cols = line.Split(',');
DataRow dr = tbl.NewRow();
for (int cIndex = 0; cIndex < numberOfColumns; cIndex++)
{
dr[cIndex] = cols[cIndex];
}
tbl.Rows.Add(dr);
}
return tbl;
}
}
}

You can try using the loop as below, please pay attention to comments as those are important
// assumption is that both dt1 and dt2 has same number of rows
// otherise while accessing dt2 we can get index out of range exception
for (int i = 0; i < dt1.Rows.Count; i++)
{
DataRow dr1 = dt1.Rows[i];
DataRow dr2 = dt2.Rows[i];
// accessing the column below would return a system.object variable,
// need to convert it to the right type using one of the convert calls, e.g. Convert.ToInt16(dr1["ColumnName"])
if (dr1["ColumnName"] == dr2["ColumnName"])
{
// do whatever you want to do here
}
}

You can return the data table which will be the difference of two input data table and later you can perform operations on the resulting data table.
CODE
/// <summary>
/// Compare two DataTables and return a DataTable with DifferentRecords
/// </summary>
/// <param name="FirstDataTable">FirstDataTable</param>
/// <param name="SecondDataTable">SecondDataTable</param>
/// <returns>DifferentRecords</returns>
public DataTable getDifferentRecords(DataTable FirstDataTable, DataTable SecondDataTable)
{
//Create Empty Table
DataTable ResultDataTable = new DataTable("ResultDataTable");
//use a Dataset to make use of a DataRelation object
using (DataSet ds = new DataSet())
{
var dataTable = new DataTable[] { FirstDataTable.Copy(), SecondDataTable.Copy() };
dataTable[0].TableName = "FirstTable";
dataTable[1].TableName = "SecondTable";
//Add tables
ds.Tables.AddRange(dataTable);
//Get Columns for DataRelation
DataColumn[] firstColumns = new DataColumn[ds.Tables[0].Columns.Count];
for (int i = 0; i < firstColumns.Length; i++)
{
firstColumns[i] = ds.Tables[0].Columns[i];
}
DataColumn[] secondColumns = new DataColumn[ds.Tables[1].Columns.Count];
for (int i = 0; i < secondColumns.Length; i++)
{
secondColumns[i] = ds.Tables[1].Columns[i];
}
//Create DataRelation
DataRelation r1 = new DataRelation(string.Empty, firstColumns, secondColumns, false);
ds.Relations.Add(r1);
DataRelation r2 = new DataRelation(string.Empty, secondColumns, firstColumns, false);
ds.Relations.Add(r2);
//Create columns for return table
for (int i = 0; i < FirstDataTable.Columns.Count; i++)
{
ResultDataTable.Columns.Add(FirstDataTable.Columns[i].ColumnName,
FirstDataTable.Columns[i].DataType);
}
//If FirstDataTable Row not in SecondDataTable, Add to ResultDataTable.
ResultDataTable.BeginLoadData();
foreach (DataRow parentrow in ds.Tables[0].Rows)
{
DataRow[] childrows = parentrow.GetChildRows(r1);
if (childrows == null || childrows.Length == 0)
{
ResultDataTable.LoadDataRow(parentrow.ItemArray, true);
}
}
//If SecondDataTable Row not in FirstDataTable, Add to ResultDataTable.
foreach (DataRow parentrow in ds.Tables[1].Rows)
{
DataRow[] childrows = parentrow.GetChildRows(r2);
if (childrows == null || childrows.Length == 0)
ResultDataTable.LoadDataRow(parentrow.ItemArray, true);
}
ResultDataTable.EndLoadData();
}
return ResultDataTable;
}

You need to first loop on the first data table
Then get row at specific index
Check whether current row exist in second data table
Get row from second data table at same index.
Read the column value from row to string variable.
Check if both value from both row are equal or not.
DataTable dt1 = ConvertToDataTable(#"C:\Users\manchunl\Desktop\Sample1.txt", 10);
DataTable dt2 = ConvertToDataTable2(#"C:\Users\manchunl\Desktop\Sample2.txt", 10);
for (int i = 0; i < dt1.Rows.Count; i++)
{
DataRow dr1 = dt1.Rows[i];
if (dt2.Rows.Count > i)
{
DataRow dr2 = dt2.Rows[i];
string value1 = Convert.ToString(dr1["Column5"]);
string value2 = Convert.ToString(dr2["Column5"]);
if (!string.IsNullOrEmpty(value1) && !string.IsNullOrEmpty(value2) && value1 == value2)
{
Console.WriteLine(value1);
}
else
{
//Do code when no matched.
}
}
}

How to Change order of columns in gridview?

I want to change order of gridview columns (8th to be first, first to be second, second to be third...). I am filling my gridview (which has 9 columns) with data from text file. Code is here:
public DataTable ConvertToDataTable(string filePath, int numberOfColumns)
{
DataTable tbl = new DataTable();
for (int col = 0; col < numberOfColumns; col++)
tbl.Columns.Add(new DataColumn("Column" + (col + 1).ToString()));
string[] lines = File.ReadAllLines(filePath);
List<string> ekran = new List<string>();
foreach (string line in lines)
{
var cols = line.Split(',');
DataRow dr = tbl.NewRow();
for (int cIndex = 0; cIndex < 9; cIndex++)
{
if (cols[cIndex].Contains('_'))
{
cols[cIndex] = cols[cIndex].Substring(0, cols[cIndex].IndexOf('_'));
dr[cIndex] = cols[cIndex];
}
else
{
cols[cIndex] += '_';
cols[cIndex] = cols[cIndex].Substring(0, cols[cIndex].IndexOf('_'));
dr[cIndex] = cols[cIndex];
}
}
for (int cIndex = 0; cIndex < 9;cIndex++ )
if (dr[cIndex].ToString() == promenljiva)
tbl.Rows.Add(dr);
}
this.GridView1.DataSource = tbl;
this.GridView1.DataBind();
return tbl;
}
After that i have this:
ConvertToDataTable(filePath, 9);
This is gridview:
<asp:GridView ID="GridView1" runat="server"></asp:GridView>
How can i do that?

Before setting the DataSource of the grid
tbl.Columns[8].SetOrdinal(0);
This will change the Ordinal property of the DataColumn inside the DataTable.DataColumnCollection in a way that the grid sees, as first column, your 9th column. Of course all other columns move up to a new index position

For further reading, it's discussed in detail here!
https://www.codeproject.com/Questions/711397/How-to-Change-order-of-columns-in-gridview
How to reorder columns in gridview dynamically
Then some add/remove column pieces with "geekwithblogs" site
http://geekswithblogs.net/dotNETvinz/archive/2009/06/03/move--autogenerate-columns-at-leftmost-part-of-the-gridview.aspx

How to add a column wise row value in data table from for loop

How to add a row in the data table
Code
DataTable dt = new DataTable();
dt.Clear();
DataColumn dc = new DataColumn("day1", typeof(String));
dt.Columns.Add(dc);
dc = new DataColumn("day2", typeof(String));
dt.Columns.Add(dc);
dc = new DataColumn("day3", typeof(String));
dt.Columns.Add(dc);
tString[0] = "Sat,mon,tue";
tString[1] = "Fri,,wed";
tString[2] = "Thu,";
int lengthA = tString.Length;
for (int i = 0; i <= lengthA - 1; i++)
{
string s = tString[i];
string[] words = s.Split(',');
foreach (string word in words)
{
dt.Rows.Add(word);
}
}
The issue in dt.Rows.Add(word) because it is inserting a row
Expected Output
Datatable value should be
day1, day2, day3
sun,mon,tue
Fri,Wed
Thu
Hot to achieve this, can any one help me

Just create a NewRow() and then add the values to its Item indexer for each column.
for (int i = 0; i <= lengthA - 1; i++)
{
string s = tString[i];
string[] words = s.Split(',');
// here is the new row
var row = dt.NewRow();
for(int w = 0; w < words.Length; w++)
{
// set each column
row[w] = words[w];
}
// don't forget to add the Row to the Rows collection
dt.Rows.Add(row);
}

how to iterate through datatable

I have data table with 100000 records, I want to iterate through data table for every 10,000 records I want to save the records. for the next iteration next 10000 records I want to save until for 100000 records.
DataTable dt = new DataTable();
dt = ds.tables[0]; //here i am getting 100,000 records
for (int i = 0; i < dt.rows.count; i + 10000)
{
savedatatable(dt[i]);
}

You should use the following code:
DataTable dt = new DataTable();
dt = ds.tables[0]; //here i am getting 100,000 records
//Loop through columns in rows
for (int i = 0; i < dt.rows.count && i < 100000; i += 10000)
{
foreach (DataColumn col in dt.Columns)
savedatatable(dt.Rows[col.ColumnName].ToString());
}
or
DataTable dt = new DataTable();
dt = ds.tables[0]; //here i am getting 100,000 records
//Loop through rows in columns
foreach (DataColumn col in dt.Columns)
{
for (int i = 0; i < dt.rows.count && i < 100000; i += 10000)
savedatatable(dt.Rows[col.ColumnName].ToString());
}
Here's a similar question, but I'm not sure if this is what you wanted. : Looping through a DataTable

Should be something like this:
for (int i = 0; i < dt.Rows.Count; i+=10000)
{
DataRow dr = dt.Rows[i];
// do something
}

Rows not showing up in DataTable c#

I am trying to copy data from my datagridview to a datatable so i can export to a csv file
here is the code
public DataTable createdatatablefromdgv()
{
DataTable dsptable = new DataTable();
for (int i = 0; i < dataGridView1.Columns.Count; i++)
{
DataColumn dspcolumn = new DataColumn(dataGridView1.Columns[i].HeaderText);
dsptable.Columns.Add(dspcolumn);
}
int noOfColumns = dataGridView1.Columns.Count;
foreach (DataGridViewRow dgvr in dataGridView1.Rows)
{
DataRow dataRow = dsptable.NewRow();
for (int i = 0; i < noOfColumns; i++)
{
dataRow[i] = dgvr.Cells[i].Value.ToString();
}
}
return dsptable;
}
It seems like it copies the data from the the grid to to the table but when I return the datatable all there is the columns no rows

You are not adding dataRow to data table after assigning values to its columns.
public DataTable createdatatablefromdgv()
{
DataTable dsptable = new DataTable();
for (int i = 0; i < dataGridView1.Columns.Count; i++)
{
DataColumn dspcolumn = new DataColumn(dataGridView1.Columns[i].HeaderText);
dsptable.Columns.Add(dspcolumn);
}
int noOfColumns = dataGridView1.Columns.Count;
foreach (DataGridViewRow dgvr in dataGridView1.Rows)
{
DataRow dataRow = dsptable.NewRow();
for (int i = 0; i < noOfColumns; i++)
{
dataRow[i] = dgvr.Cells[i].Value.ToString();
}
dsptable.Rows.Add(dataRow); //Add this statement to add rows to Data Table
}
return dsptable;
}

The above answer is correct but a little explanation as to why you encountered this problem. One would think that by calling NewRow() on the DataTable you would add a new row to the DataTable and then be able to access it.
What NewRow actually does is give you an instance of a DataRow which you can then use column names as apose to column identifiers (integers).
This allows you to do something like this
DataRow dataRow = dsptable.NewRow();
foreach(DataColumn dc in dsptable.Columns)
{
dataRow[dc.ColumnName] = dgvr.Cells[dc.ColumnName].Value.ToString()
}
Alternatively you could just call Rows.Add() which takes an object array or a as you were trying to do a DataRow.
List<string> rowData = new List<string>();
for (int i = 0; i < noOfColumns; i++)
{
rowData.Add(dgvr.Cells[i].Value.ToString());
}
dsptable.Rows.Add(rowData.ToArray());
This should explain adding rows to a datatable more simply :)

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