Selecting data from a datatable in PowerShell - powershell

Question

I'm trying to figure out how to get the data i need from a Datatable.
I'm new to datatables and cannot figure out by reading the documentation how to properly build the needed query.
I made a test script in PowerShell that i posted below:
# clear the screen:
CLS
# Create the Datatable:
$dt1 = New-Object System.Data.Datatable
# Name the datatable:
$dt1.TableName = "MyTable"
# Add collumns to the table:
[void]$dt1.Columns.Add("datacolumnone")
[void]$dt1.Columns.Add("datacolumntwo")
[void]$dt1.Columns.Add("datacolumnthree")
# Add data:
[void]$dt1.Rows.Add([string]"id 1", [string]"fact 1", [string]"purple")
[void]$dt1.Rows.Add([string]"id 1", [string]"fact 2", [string]"black")
[void]$dt1.Rows.Add([string]"id 1", [string]"fact 3", [string]"green")
[void]$dt1.Rows.Add([string]"id 1", [string]"fact 4", [string]"green")
[void]$dt1.Rows.Add([string]"id 2", [string]"fact 1", [string]"blue")
[void]$dt1.Rows.Add([string]"id 2", [string]"fact 2", [string]"yellow")
[void]$dt1.Rows.Add([string]"id 2", [string]"fact 3", [string]"purple")
[void]$dt1.Rows.Add([string]"id 2", [string]"fact 4", [string]"yellow")
[void]$dt1.Rows.Add([string]"id 3", [string]"fact 1", [string]"purple")
[void]$dt1.Rows.Add([string]"id 3", [string]"fact 2", [string]"black")
[void]$dt1.Rows.Add([string]"id 3", [string]"fact 3", [string]"green")
[void]$dt1.Rows.Add([string]"id 3", [string]"fact 4", [string]"yellow")
[void]$dt1.Rows.Add([string]"id 4", [string]"fact 1", [string]"purple")
[void]$dt1.Rows.Add([string]"id 4", [string]"fact 2", [string]"yellow")
[void]$dt1.Rows.Add([string]"id 4", [string]"fact 3", [string]"purple")
[void]$dt1.Rows.Add([string]"id 4", [string]"fact 4", [string]"yellow")
# Write the data to a xml and data file:
$dt1.WriteXmlSchema('.\CacheSchema.xsd')
$dt1.WriteXml(".\CacheData.xml")
##############################
# End of this script #
# Going on with the next one #
##############################
# Set the search criteria:
$column1 = ""
$column2 = "fact 1"
$column3 = "purple"
# build the query:
$qquery1 = "
datacolumnone like '%"+$column1+"%'
AND datacolumntwo like '%"+$column2+"%'
AND datacolumnthree like '%"+$column3+"%'
";
# Create the Datatable:
$dt2 = New-Object System.Data.Datatable
# Load the data:
[void]$dt2.ReadXmlSchema(".\CacheSchema.xsd")
[void]$dt2.ReadXml(".\CacheData.xml")
# Run the query:
$dt2.Select($qquery1)
Now what i try to achieve is:
Find all id's (datacolumnone) from the rows that have the value: "fact 1" in "datacolumntwo" and "purple" in "datacolumnthree"
Then further filter the id's where "datacolumnone" is in the results from the query above, "datacolumntwo" is "fact 4" and
"datacolumnthree" is "yellow"
Then when we have the filtered id's, show the rows that have in "datacolumnone" an id from the filtered query above and in
"datacolumntwo" the value "fact 2"
https://msdn.microsoft.com/en-us/library/system.data.datatable.select%28v=vs.110%29.aspx

Answer 1

If I am understanding the question correctly, querying a DataTable is the same as selecting rows that meet certain criteria using the Pipeline:
So, query one would be:
$results1 = $dt | Where-Object {$.datacolumntwo -eq "fact 1" -and $.datacolumnthree -eq "purple"} | Select Id
And query2 would be:
$results2 = $dt | Where-Object {$.datacolumnone -in $result1 -and $.datacolumntwo -eq "fact 4" -and $_.datacolumnthree -eq "yellow"} | Select Id
or you can combine the two queries if the intermediate results are not needed.