Compare-TwoCsvFiles.ps1

 <#
	.SYNOPSIS
    Compares two CSV files using a common field.

	.DESCRIPTION
	  Compares two CSV files using an index, or common field to flag and find rows with that matching field instead of comparing the files row by row, sequentially.
    This will typically be used with files that have matching syntax and output from the same application or service. The oldest version of the two files being compared
    should be Csv1. The newest version of the files being compared should be Csv2. 

	.PARAMETER  Csv1FilePath
		The path of the first Csv file. This should read the same as the expected parameter value for 'Import-Csv -Path'.

	.PARAMETER  Csv2FilePath
		The path of the second Csv file. This should read the same as the expected parameter value for 'Import-Csv -Path'.

	.PARAMETER  CsvIndexField
		This is a string used in a field that both files have in common. This will be used to find corresponding rows in both files, as the files are not compared row by row, sequentially.

	.PARAMETER  CsvSharedField1
		Another field that both files share. The values in these fields will be compared whenever a matching row is found between both files using the parameter value of CsvIndexField.

	.EXAMPLE
		PS C:\> Compare-TwoCsvFiles -Csv1FilePath 'C:\File1.Csv' -Csv2FilePath 'C:\File2.Csv' -CsvIndexField 'Username' -CsvSharedField1 'Birthday'

    PS C:\> $DeltaHashTable

		Name             Value
    ----             -----
    Bob              { Birthday }
    Jim              { Birthday }

    PS C:\> $DeltaHashTable.('Bob')

		Name             Value
    ----             -----
    Birthday         4/4/84

		This example shows how to call the function and explore its output.

	.INPUTS
		System.String

	.OUTPUTS
		System.Collections.Hashtable

	.LINK
		about_functions_advanced

	.LINK
		about_comment_based_help

	.LINK
		about_functions_advanced_parameters

	.LINK
		about_functions_advanced_methods
    #>

    function Compare-TwoCsvFiles {
    [CmdletBinding()]
    param(
    [Parameter(Position=0, Mandatory = $True)]
    [System.String]
    $Csv1FilePath,
    [Parameter(Position = 1, Mandatory = $True)]
    [System.String]$Csv2FilePath,
    [Parameter(Position = 2, Mandatory = $True)]
    [System.String]$CsvIndexField,
    [Parameter(Position = 3)]
    [System.String]$CsvSharedField1,
    [Parameter(Position = 4)]
    [System.String]$CsvSharedField2,
    [Parameter(Position = 5)]
    [System.String]$CsvSharedField3,
    [Parameter(Position = 6)]
    [System.String]$CsvSharedField4,
    [Parameter(Position = 7)]
    [System.String]$CsvSharedField5
    )
	
    BEGIN
    {
    $Csv1 = Import-Csv -Path $Csv1FilePath
    $Csv2 = Import-Csv -Path $Csv2FilePath
		
    $Csv1RowCount = $Csv1.Count
    $Csv2RowCount = $Csv2.Count
		
    If ($Csv1RowCount -gt $Csv2RowCount)
    { $RowDeltaCount = $Csv1RowCount - $Csv2RowCount }
    Else { $RowDeltaCount = $Csv2RowCount - $Csv1RowCount }
		
    [System.Collections.ArrayList]$Csv1IndexField = $Csv1.$CsvIndexField
    [System.Collections.ArrayList]$Csv2IndexField = $Csv2.$CsvIndexField
		
     }
	
    PROCESS
    {
    $CsvIndexFieldComparison = Compare-Object -ReferenceObject $Csv1IndexField -DifferenceObject $Csv2IndexField -IncludeEqual
    $CsvSharedIndexFields = $CsvIndexFieldComparison | Where-Object { $_.SideIndicator -eq '==' } | Select-Object -ExpandProperty InputObject
		
    $Dataset = @{ }
		
    ForEach ($Row in $Csv1) { $Dataset[$Row.$CsvIndexField] = @{ 'Csv1' = $Row } }
    ForEach ($Row in $Csv2) { If ($Dataset[$Row.$CsvIndexField]) { $Dataset[$Row.$CsvIndexField].Csv2 = $Row } Else { $Dataset[$Row.$CsvIndexField] = @{ 'Csv2' = $Row } } }
		
    $DeltaHashTable = @{ }
		
    ForEach ($Item in $Dataset.Keys)
    {
      If ($Dataset.($Item).Csv1 -and $Dataset.($Item).Csv2)
      {
        $Csv1HashCode = ($Dataset.$Item.Csv1 | Out-String).GetHashCode()
        $Csv2HashCode = ($Dataset.$Item.Csv2 | Out-String).GetHashCode()
        
        If($Csv1HashCode -ne $Csv2HashCode)
        {
				
          
          If($CsvSharedField1){ If ($Dataset.$Item.Csv1.$CsvSharedField1.GetHashCode() -ne $Dataset.$User.Csv2.$CsvSharedField1.GetHashCode()) { $DeltaHashTable += @{ $Item = @{ $CsvSharedField1 = $($Dataset.$Item.Csv2.$CsvSharedField1) } } } }       
          If($CsvSharedField2){ If ($Dataset.$Item.Csv1.$CsvSharedField2.GetHashCode() -ne $Dataset.$User.Csv2.$CsvSharedField2.GetHashCode()) { $DeltaHashTable += @{ $Item = @{ $CsvSharedField2 = $($Dataset.$Item.Csv2.$CsvSharedField2) } } } }
          If($CsvSharedField3){ If ($Dataset.$Item.Csv1.$CsvSharedField3.GetHashCode() -ne $Dataset.$User.Csv2.$CsvSharedField3.GetHashCode()) { $DeltaHashTable += @{ $Item = @{ $CsvSharedField3 = $($Dataset.$Item.Csv2.$CsvSharedField3) } } } }
          If($CsvSharedField4){ If ($Dataset.$Item.Csv1.$CsvSharedField4.GetHashCode() -ne $Dataset.$User.Csv2.$CsvSharedField4.GetHashCode()) { $DeltaHashTable += @{ $Item = @{ $CsvSharedField4 = $($Dataset.$Item.Csv2.$CsvSharedField3) } } } }
          If($CsvSharedFIeld5){ If ($Dataset.$Item.Csv1.$CsvSharedField5.GetHashCode() -ne $Dataset.$User.Csv2.$CsvSharedField5.GetHashCode()) { $DeltaHashTable += @{ $Item = @{ $CsvSharedField5 = $($Dataset.$Item.Csv2.$CsvSharedField5) } } } }
        
          }
        }
      }
    }
	
    END
    {
		$DeltaHashTable
    }
  
    }