Add custom field to DataTable. OleDbDataAdapter

Question

Code works fine until I try to add a custom column using:

$datatable.Columns.Add("AD_description1", "String")

If I comment the string I can perfectly see results in GridView. But once the string uncommented the gridview displays:

How do I add a custom field properly?

$adapter = New-Object System.Data.OleDb.OleDbDataAdapter($QueryString, $ConnectionString)

#Load the DataTable
$datatable = New-Object System.Data.DataTable
[void]$adapter.Fill($datatable)
$datatable.Columns.Add("AD_description1", "String")
$datatable | out-gridview

Answer 1

See these results:

$adapter = New-Object System.Data.OleDb.OleDbDataAdapter($QueryString, $ConnectionString)

#Load the DataTable
$datatable = New-Object System.Data.DataTable
[void]$adapter.Fill($datatable)
$datatable.Columns.Add("AD_description1", "String")
$datatable
# Results
<#
AllowDBNull        : True
AutoIncrement      : False
AutoIncrementSeed  : 0
AutoIncrementStep  : 1
Caption            : AD_description1
ColumnName         : AD_description1
Prefix             : 
DataType           : System.String
DateTimeMode       : UnspecifiedLocal
DefaultValue       : 
Expression         : 
ExtendedProperties : {}
MaxLength          : -1
Namespace          : 
Ordinal            : 0
ReadOnly           : False
Table              : {}
Unique             : False
ColumnMapping      : Element
Site               : 
Container          : 
DesignMode         : False
#>

$adapter = New-Object System.Data.OleDb.OleDbDataAdapter($QueryString, $ConnectionString)

#Load the DataTable
$datatable = New-Object System.Data.DataTable
[void]$adapter.Fill($datatable)
$datatable.Columns.Add("AD_description1")
$datatable.Columns.Add("SomeString")
$datatable


# Results
<#
AllowDBNull        : True
AutoIncrement      : False
AutoIncrementSeed  : 0
AutoIncrementStep  : 1
Caption            : AD_description1
ColumnName         : AD_description1
Prefix             : 
DataType           : System.String
DateTimeMode       : UnspecifiedLocal
DefaultValue       : 
Expression         : 
ExtendedProperties : {}
MaxLength          : -1
Namespace          : 
Ordinal            : 0
ReadOnly           : False
Table              : {}
Unique             : False
ColumnMapping      : Element
Site               : 
Container          : 
DesignMode         : False

AllowDBNull        : True
AutoIncrement      : False
AutoIncrementSeed  : 0
AutoIncrementStep  : 1
Caption            : SomeString
ColumnName         : SomeString
Prefix             : 
DataType           : System.String
DateTimeMode       : UnspecifiedLocal
DefaultValue       : 
Expression         : 
ExtendedProperties : {}
MaxLength          : -1
Namespace          : 
Ordinal            : 1
ReadOnly           : False
Table              : {}
Unique             : False
ColumnMapping      : Element
Site               : 
Container          : 
DesignMode         : False
#>

References:

Adding Columns to a DataTable | MSDocs

How To Create a DataTable In Powershell