DataTable, compare rowsDataTables sometimes have equal rows. How can you compare these rows between tables? A transformation can be applied to each cell.
With the C# code in this example, we loop over both DataTables in nested foreach-loops. We call SequenceEqual to compare the data in each row.
DataTables have no built-in methods for complicated comparison operations. Here, we introduce the CompareRows method.
CompareRows receives 2 DataTable instances. Then it loops over all the rows in both DataTables with nested loops.ItemArray property on both DataRow instances at the present position.SequenceEqual from System.Linq to determine if the arrays are exactly equal in length and element composition.for-loop.DataTable has a DataRow with the name "Enebrel" and a dosage of 50 mg.using System;
using System.Data;
using System.Linq;
class Program
{
static void CompareRows(DataTable table1, DataTable table2)
{
foreach (DataRow row1 in table1.Rows)
{
foreach (DataRow row2 in table2.Rows)
{
var array1 = row1.ItemArray;
var array2 = row2.ItemArray;
if (array1.SequenceEqual(array2))
{
Console.WriteLine("Equal: {0} {1}",
row1["Drug"], row2["Drug"]);
}
else
{
Console.WriteLine("Not equal: {0} {1}",
row1["Drug"], row2["Drug"]);
}
}
}
}
static DataTable GetTable1()
{
DataTable table = new DataTable();
table.Columns.Add("Dosage", typeof(int));
table.Columns.Add("Drug", typeof(string));
table.Columns.Add("Patient", typeof(string));
table.Rows.Add(25, "Indocin", "David");
table.Rows.Add(50, "Enebrel", "Cecil");
return table;
}
static DataTable GetTable2()
{
DataTable table = new DataTable();
table.Columns.Add("Dosage", typeof(int));
table.Columns.Add("Drug", typeof(string));
table.Columns.Add("Patient", typeof(string));
table.Rows.Add(21, "Combivent", "Janet");
table.Rows.Add(50, "Enebrel", "Cecil");
table.Rows.Add(10, "Hydralazine", "Christoff");
return table;
}
static void Main()
{
CompareRows(GetTable1(), GetTable2());
}
}Not equal: Indocin Combivent
Not equal: Indocin Enebrel
Not equal: Indocin Hydralazine
Not equal: Enebrel Combivent
Equal: Enebrel Enebrel
Not equal: Enebrel HydralazineSometimes we wish to transform the data in rows before comparing. For example, we may need to see that each decimal in a row has a certain relation to another cell.
GetDecimals(), which extracts all the decimal data from a row.GetDecimals(), we can validate that the decimals in table 2 are 1.5 times greater.using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
class Program
{
static List<decimal> GetDecimals(object[] array, decimal multiplier)
{
// Add all decimals in the row to a List of decimals.
// ... And return the list.
var list = new List<decimal>();
foreach (object value in array)
{
try
{
decimal result = (decimal)value;
result *= multiplier;
list.Add(result);
}
catch
{
// Error.
}
}
return list;
}
static void CompareRows(DataTable table1, DataTable table2)
{
foreach (DataRow row1 in table1.Rows)
{
foreach (DataRow row2 in table2.Rows)
{
// Get decimals in each row.
// ... Multiply items in row 1 by 1.5.
var decimals1 = GetDecimals(row1.ItemArray, (decimal)1.5);
var decimals2 = GetDecimals(row2.ItemArray, (decimal)1.0);
// See if the row is valid.
if (decimals1.SequenceEqual(decimals2))
{
Console.WriteLine("OK: " + decimals1[0]);
}
else
{
Console.WriteLine("NOT OK: " + decimals1[0]);
}
}
}
}
static DataTable GetTable1()
{
var table = new DataTable { TableName = "Prices in Sterling" };
table.Columns.Add("Product", typeof(string));
table.Columns.Add("Variety1", typeof(decimal));
table.Columns.Add("Variety2", typeof(decimal));
table.Columns.Add("Variety3", typeof(decimal));
table.Columns.Add("Variety4", typeof(decimal));
table.Rows.Add("Product 1", 10, 12, 14, 45);
table.Rows.Add("Product 2", 20, 15, 24, null);
table.Rows.Add("Product 3", 22, 60, null, null);
table.Rows.Add("Product 4", 28, null, null, null);
var sum1 = (decimal)table.Compute("SUM(Variety1)", string.Empty);
var sum2 = (decimal)table.Compute("SUM(Variety2)", string.Empty);
var sum3 = (decimal)table.Compute("SUM(Variety3)", string.Empty);
var sum4 = (decimal)table.Compute("SUM(Variety4)", string.Empty);
table.Rows.Add("Total", sum1, sum2, sum3, sum4);
return table;
}
static DataTable GetTable2()
{
var table = new DataTable { TableName = "Prices in Euro" };
table.Columns.Add("Product", typeof(string));
table.Columns.Add("Variety1", typeof(decimal));
table.Columns.Add("Variety2", typeof(decimal));
table.Columns.Add("Variety3", typeof(decimal));
table.Columns.Add("Variety4", typeof(decimal));
table.Rows.Add("Product 1", 15, 18, 21, 67.5);
table.Rows.Add("Product 2", 30, 22.5, 36, null);
table.Rows.Add("Product 3", 33, 90, null, null);
table.Rows.Add("Product 4", 42, null, 24, null);
decimal sum1 = (decimal)table.Compute("SUM(Variety1)", string.Empty);
decimal sum2 = (decimal)table.Compute("SUM(Variety2)", string.Empty);
decimal sum3 = (decimal)table.Compute("SUM(Variety3)", string.Empty);
decimal sum4 = (decimal)table.Compute("SUM(Variety4)", string.Empty);
table.Rows.Add("Total", sum1, sum2, sum3, sum4);
return table;
}
static void Main()
{
CompareRows(GetTable1(), GetTable2());
}
}OK: 15.0
NOT OK: 15.0
NOT OK: 15.0
NOT OK: 15.0
NOT OK: 15.0
NOT OK: 30.0
OK: 30.0
NOT OK: 30.0
NOT OK: 30.0
NOT OK: 30.0
NOT OK: 33.0
NOT OK: 33.0
OK: 33.0
NOT OK: 33.0
NOT OK: 33.0
NOT OK: 42.0
NOT OK: 42.0
NOT OK: 42.0
NOT OK: 42.0
NOT OK: 42.0
NOT OK: 120.0
NOT OK: 120.0
NOT OK: 120.0
NOT OK: 120.0
NOT OK: 120.0Often converting DataTable rows into Lists and then working on the Lists is easier. In C#, using Lists tends to be a good approach to problems.
For comparing the rows in 2 DataTables, you do not need to have nested loops. We can just do a linear scan through 2 DataTables to compare them.
The rows in DataTables can be compared using SequenceEqual. We can determine the equality or near-equality of 2 DataRows with the elements in the ItemArray property.