how to read unique values from excel column using powershell - powershell

Question

i would like to read unique email id from a column and assign to a local variable, can anyone assist in doing that
my data will be like
i would like to get unique values from the excel and assign it to a variable using power shell
the variable should hold value in following way Nalin23#bridgestone.com;raj#bridgestone.com;kishan#bridgestone.com

Answer 1

To read the values from an Excel column and return it as array of values, you can use this helper function:
function Import-ExcelColumn {
# returns an array of Excel Column values
[CmdletBinding()]
Param (
[Parameter(Mandatory = $true, ValueFromPipeline = $true, ValueFromPipelineByPropertyName = $true, Position = 0)]
[string]$Path,
[Parameter(Mandatory = $false, Position = 1)]
[int]$WorkSheetIndex = 1,
[Parameter(Mandatory = $false, Position = 2)]
[int]$ColumnIndex = 1
)
# constants from https://learn.microsoft.com/en-us/office/vba/api/excel.xldirection
$xlDown = -4121
$xlUp = -4162
$excel = New-Object -ComObject Excel.Application
$excel.Visible = $false
$workbook = $excel.Workbooks.Open($Path)
$worksheet = $workbook.Worksheets.Item($WorkSheetIndex)
# get the first and last used row indices
$firstRow = $worksheet.Cells($worksheet.UsedRange.Rows.Count, 1).End($xlUp).Row
$lastRow = $worksheet.Cells($firstRow, 1).End($xlDown).Row
# collect the values in this column in variable $result
# start at $firstRow + 1 to skip the header itself
$result = for ($row = $firstRow + 1; $row -le $lastRow; $row++) {
$worksheet.Cells.Item($row, $ColumnIndex).Value2
}
$excel.Quit()
# IMPORTANT: clean-up used Com objects
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($worksheet) | Out-Null
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($workbook) | Out-Null
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($excel) | Out-Null
[System.GC]::Collect()
[System.GC]::WaitForPendingFinalizers()
# $result is an array. PowerShell 'unravels' arrays when returned from a function.
# to overcome this, prefix the returned array with a unary comma.
return ,$result
}
After that, in your case use it like this:
$emailAddresses = ((Import-ExcelColumn -Path 'D:\Test\Map1.xlsx' -ColumnIndex 2) | Select-Object -Unique) -join ';'
to get a string:
Nalin23#bridgestone.com;raj#bridgestone.com;kishan#bridgestone.com

Answer 2

Please show the code you have attempted as a reference for everyone answering the qustion.
With that said, the below code should work for a comma separate value (.csv) file:
# Get CSV object
$csv_object = Import-CSV $path_to_csv
# Find unique entries from email_id column
$unique_emails = $csv_object.email_id | Select -Unique
# Join them with ;
$delim_emails = $unqiue_emails -join ";"