Powershell - copying or adding to a Datatable? - tsql

Question

I'm using Chad Miller & Hey Scripting Guy's functions invoke-sqlcmd2 and write-datatable to save the results of a query to a datatable, then write it into a SQL table.
Here's the code I'm running:
$dt = invoke-sqlcmd2 -serverinstance $_.server -query "exec master.dbo.sp_who" -As 'Datatable'
write-datatable -serverinstance "myserverhere" -DATABASE "dbainfo" -tablename "who_sp_results" -DATA $dt
I want to add a field to the datatable - I'm running an SP I can't modify, and want to add the servername. I'm running it in parallel, so I can't use a staging table, I have to either modify the existing datatable or move it to a new datatable.
How do I copy/alter a datatable to get the additional column and set it to another variable?
If we use a second datatable, since I'm looping, how do I "truncate"
it or clear it out prior to the next run within the foreach loop?
UPDATE: added one row from $dt | select-object * , and $dt | get-member
spid : 1
ecid : 0
status : background
loginame : sa
hostname :
blk : 0
dbname :
cmd : RESOURCE MONITOR
request_id : 0
RowError :
RowState : Unchanged
Table : {sa, sa, sa, sa...}
ItemArray : {1, 0, background , sa...}
HasErrors : False
Here's the results from $dt | get-member :
TypeName: System.Data.DataRow
Name MemberType Definition
---- ---------- ----------
AcceptChanges Method System.Void AcceptChanges()
BeginEdit Method System.Void BeginEdit()
CancelEdit Method System.Void CancelEdit()
ClearErrors Method System.Void ClearErrors()
Delete Method System.Void Delete()
EndEdit Method System.Void EndEdit()
Equals Method bool Equals(System.Object obj)
GetChildRows Method System.Data.DataRow[] GetChildRows(string relationName), System.Data.DataRow[] GetChildRows(...
GetColumnError Method string GetColumnError(int columnIndex), string GetColumnError(string columnName), string Get...
GetColumnsInError Method System.Data.DataColumn[] GetColumnsInError()
GetHashCode Method int GetHashCode()
GetParentRow Method System.Data.DataRow GetParentRow(string relationName), System.Data.DataRow GetParentRow(stri...
GetParentRows Method System.Data.DataRow[] GetParentRows(string relationName), System.Data.DataRow[] GetParentRow...
GetType Method type GetType()
HasVersion Method bool HasVersion(System.Data.DataRowVersion version)
IsNull Method bool IsNull(int columnIndex), bool IsNull(string columnName), bool IsNull(System.Data.DataCo...
RejectChanges Method System.Void RejectChanges()
SetAdded Method System.Void SetAdded()
SetColumnError Method System.Void SetColumnError(int columnIndex, string error), System.Void SetColumnError(string...
SetModified Method System.Void SetModified()
SetParentRow Method System.Void SetParentRow(System.Data.DataRow parentRow), System.Void SetParentRow(System.Dat...
ToString Method string ToString()
Item ParameterizedProperty System.Object Item(int columnIndex) {get;set;}, System.Object Item(string columnName) {get;s...
blk Property System.String blk {get;set;}
cmd Property System.String cmd {get;set;}
dbname Property System.String dbname {get;set;}
ecid Property System.Int16 ecid {get;set;}
hostname Property System.String hostname {get;set;}
loginame Property System.String loginame {get;set;}
request_id Property System.Int32 request_id {get;set;}
spid Property System.Int16 spid {get;set;}
status Property System.String status {get;set;}

Answer 1

You don't want to use add-member as this won't add a type of datacolumn. Instead do the following:
$Col = new-object Data.DataColumn
$Col.ColumnName = "ServerName"
$dt.Columns.Add($col)
$dt | %{$_.ServerName = "myserverName"}
BTW if you use get-member with inputobject parameter you'll see the columns and add method:
gm -inputobject $dt
This is different than
$dt | gm which returns properties and methods of datarows. The first one doesn't unroll.

Answer 2

I think you are looking for Add-Member