Compare 2 csv files and match based on 1 column then export new file that contains fields from both - powershell

Question

I have 2 csv files. Each have different headers and different number of columns, and have different number of entries.
Here are some examples of the first couple lines
CSV 1
ID,Last_Name,First_Name,Middle_Name,Email_Addr,Title,Gender
###1,smith,bill,p,smith#soso.com,boss,m
###2,smith2,billy,p,smith2#soso.com,someguy,m
CSV 2
ID,Name Id,Last Name,First Name,Middle Name,Gender
###2,ID1010,smith2,billy,p,M
I am trying to import them and compare the ID column. When a match is found I am wanting a new csv file with All info from CSV 1 and the matched Name ID from csv 2.
New CSV Example:
ID,Last_Name,First_Name,Middle_Name,Email_Addr,Title,Gender,Name Id
###1,smith,bill,p,smith#soso.com,boss,m,
###2,smith2,billy,p,smith2#soso.com,someguy,m,ID1010
Ive been looking and came across this Stackoverflow from about a year ago that seemed to be on the right track but I cant seem to get code modified for my needs. Here is what I have tried.
$csv1 = Import-Csv -Path C:\STAFF\test1sky.csv
$csv2 = Import-Csv -Path C:\STAFF\test1power.csv
ForEach($Record in $csv2){
$MatchedValue = (Compare-Object $csv1 $Record -Property "ID" -IncludeEqual -ExcludeDifferent -PassThru).value
$Record = Add-Member -InputObject $Record -Type NoteProperty -Name "Name Id" -Value $MatchedValue
}
$csv2|Export-Csv 'C:\STAFF\combined.csv' -NoTypeInformation
I get the correct header in the new file but I never get the Name ID values to come though.
Any idea where I went wrong? I maybe on the wrong path completely and there be a easier way, but I need to be able to do this nightly without user interaction. Any help is appreciated!!

Answer 1

Let's try to simplify this. Add the 'Name ID' field to all records in CSV1. Then loop through it, and get the matches, and update the field. Something like:
$CSV1 = C:\Path\To\File1.csv
$CSV2 = C:\Path\To\File2.csv
$CSV1|ForEach{$_|Add-Member 'Name ID' $Null}
ForEach($Record in $CSV1){
$Record.'Name ID' = $CSV2|Where{$_.ID -eq $Record.ID}|Select -Expand 'Name ID'
}

Answer 2

$CSV1 = import-csv C:\Path\To\File1.csv
$CSV2 = import-csv C:\Path\To\File2.csv
#adds a row named "Name ID" to the PS Object( the CSV Import)
$CSV1|ForEach{$_|Add-Member 'Name ID' $Null}
ForEach($Record in $CSV1){
#gets the value from CSV1 for comparing to CSV2
$NameValue=Record."Last_Name"
#gets the Power Shell Object from the CSV2 Import that matches the Name ID from $csv1
$Nameobject= $CSV2|Where-object "Last Name" -contains $Namevalue
#Sets the Field "Name ID" in the PS Object $CSV1 Record to the Name ID from $csv2
$record."Name ID" = $Nameobject."Name ID"
}
You can easily grab addtional fields by adding other references to the CSV1 File by manipulating the CSV2 PS Object.
$record."Middle Name" = $nameobject."Middle_Name"
Since you have the entire object in the for loop form $csv2 you can call any of its fields or manipulate them by using variables and " |select -Property "Value" Like this
$objlength = $nameobject |select "First_Name"
$objlength.length
but i prefer to call it directly from the object as the output looks cleaner like this
$nameobject."First_Name".length

Answer 3

The operation you are looking for is called a relational join. Sometimes it's called an inner join, and sometimes just a join. My knowledge of join comes from SQL, not from Powershell.
Here's a description of "Join-Object". It seems to be what you are looking for.
http://blogs.msdn.com/b/powershell/archive/2012/07/13/join-object.aspx