Check if object is in a list of objects

Question

As PowerShell has many SQL query-like cmdlets, is there a fast way to check if object is in list of other objects with the Where-Object cmdlet?

Something like in SQL:

SELECT column_name(s) FROM table_name WHERE column_name IN (value1,value2,...) 

Of course I can write a simple subroutine, but I was just wondering if there is such feature.

Answer 1

You can use the -contains operator:

Get-ColumnNames $table | Where-Object { value1,value2,... -contains $_ } 

It's backwards, though with the collection of values on the left side.

In PowerShell 3 you can also use the -in operator:

Where-Object { $_ -in value1,value2,... } 

or even

Where-Object -In value1,value2,... 

Also, a quirk of how PowerShell works with comparison operators, you can apply them directly to a collection on the left side:

Where-Object { value1,value2,... -eq $_ } 

The -eq operator here will either yield the respective element if it is in the list, or $null (which coerces to $false).