Delete particular items in SharePoint document library - powershell

Question

I want to create PowerShell script that will be run daily by time scheduler.
Documents that should be deleted will have Yes value in column1.
Bellow is my code, but I am not sure why it doesn't work
$web = get-spweb "URL"
$Libraries = $web.Lists | where {$_.BaseType -eq "DocumentLibrary"}
foreach ($library in $Libraries) {
$items = $library.items
foreach ($item in $items)
{
If($item["Column1"] -eq "Yes")
{
$item.delete()
}
}
}
Any suggestion what I did wrong?
EDIT:
After I ran script it didn't give me any error message, but instead documents weren't deleted.
EDIT2: After code edit I got following message:
Collection was modified; enumeration operation may not execute. At
C:\Users\user\Desktop\DeleteItems.ps1:5 char:14
+ foreach ($item in $items)
+ ~~~~~
+ CategoryInfo : OperationStopped: (:) [], InvalidOperationException
+ FullyQualifiedErrorId : System.InvalidOperationException

Answer 1

The reason your code is not working is because you are attempting to delete items from an enumeration inside of a foreach loop. Most collections in .NET with throw an exception if an item is added or deleted during a foreach loop.
Try a regular for loop and see what happens:
$web = get-spweb "URL"
$Libraries = $web.Lists | where {$_.BaseType -eq "DocumentLibrary"}
foreach ($library in $Libraries) {
$items = $library.items
for ($i=0; $i -lt $items.Count; $i++)
{
If($items[$i]["Column1"] -eq "Yes")
{
$items[$i].delete()
}
}
}
That may be enough, but powershell might throw an exception for the outer foreach loop too since technically you're modifying the document libraries inside the loop. If that is the case, you'll need to use a for loop on the outside too.
Also, one way to speed up your powershell is to use a caml query on the document libraries so that it only returns the items where Column1 = yes (I'm assuming Column1 is a Yes/No field). That would look like this:
$web = get-spweb "URL"
$Libraries = $web.Lists | where {$_.BaseType -eq "DocumentLibrary"}
foreach ($library in $Libraries) {
$query = New-Object Microsoft.SharePoint.SPQuery
$query.Query = "<Where><Eq><FieldRef Name='Column1'/><Value Type='Boolean'>1</Value></Eq></Where>"
$items = $library.GetItems($query)
for ($i=0; $i -lt $items.Count; $i++)
{
$items[$i].delete()
}
}