Adding more functionality to SQL Server BCP with PowerShell

<#
.Synopsis
   Bulk Copy Query Data to CSV file
.DESCRIPTION
   Bulk Copy Data from a query against a SQL Server Database into a CSV file
.EXAMPLE
   bcp-data -ServerInstance localhost -Database mssqltips -Query "select * from dbo.MyTable -FilePath c:\temp\mytable.txt -Trim Y
.INPUTS
   None
    You cannot pipe objects into BCP-Data
.OUTPUTS
   No output
.NOTES
   ver 1.0 - Jeffrey Yao 2016/Jun/01
#>

#Requires -Version 3.0
add-type -AssemblyName "System.Data";

function BCP-Data
{
    [CmdletBinding()]

    Param
    (
        # SQL Server Instance name with default to local servername
        [Parameter(Mandatory=$false)] [string]$ServerInstance=$env:ComputerName,

        # Database name with default to 'master'
        [Parameter(Mandatory=$false)] [string] $Database='master',

        # Query, the query will return a result set
        [Parameter(Mandatory=$true)]  [String] $Query,

        # FilePath, the full path name
        [Parameter(Mandatory=$true)]  [String] $FilePath,

        # FieldTerminator, the separator between columns, default to "|"
        [Parameter(Mandatory=$false)]  [String] $FieldTerminator="|",

        # RowTerminator, the separator between rows, default to a new line "`r`n"
        [Parameter(Mandatory=$false)]  [String] $RowTerminator="`r`n",

        # QuoteMark, the quoting marks around columns, default to none
        [Parameter(Mandatory=$false)]  [String] $QuoteMark="",

        # NoHeader, a switch parameter to decide whether column header are included in the csv file, by default, there is always a header unless this switch parameter is present
        [Parameter(Mandatory=$false)]  [switch] $NoHeader,

        # Trim, decides whether to trim the column of string data type, N = no trim, Y=trim both left and right of the string, L=left trim, R=right trim
        [Parameter(Mandatory=$false)]  
        [ValidateSet('N', 'Y', 'L', 'R')] [String] $Trim='N'
    )

    #we assume use windows authentication, otherwise, you need to provide User and PassWord for connection
    $conn = new-object System.Data.SQLClient.SqlConnection ("server=$ServerInstance; database=$Database; trusted_connection=true"); 
    $sqlcmd = New-Object System.Data.SqlClient.SqlCommand($query, $conn)
    $conn.Open();

    $dr = $sqlcmd.ExecuteReader();
    $dt = New-Object System.Data.DataTable;
    $dt.Load($dr);

    $sw = new-object System.IO.StreamWriter($FilePath, $false);

    #we first write the header

    if (-not $NoHeader)
    {    
        [string]$head=$dt.Columns.columnname -join $FieldTerminator;
        $sw.Write($head);
        $sw.write($RowTerminator);
    }

    foreach ( $r in $dt.rows)
    {
        [string]$tf = $FieldTerminator;
        for ([int]$i=0; $i -lt $dt.Columns.count; $i++)
        {
            if ($i -eq $dt.Columns.count -1 ) #last column does not need to be followed by $FieldTerminator
            { [string]$tf='';}
            
            if ($r[$i] -ne [System.DBNull]::Value)
            {
                if ($r[$i].GetType().name -ne 'Boolean')
                {
                    $col_val = $r[$i].ToString() ;
                }
                else
                {
                    if($r[$i] -eq $true) {  $col_val= '1' } else {$col_val='0'}  
                }  
                $col_val = $QuoteMark + $(
                    switch ($trim)
                    {
                        'Y' { $col_val.Trim() }
                        'N' { $col_val }
                        'R' { $col_val.TrimEnd()}
                        'L' { $col_val.TrimStart()}
                    }
                ) + $QuoteMark + $tf;
                $sw.Write($col_val);
            }
            else
            { $sw.Write($QuoteMark+$QuoteMark+$tf);}
        } #loop through columns

        $sw.Write($RowTerminator);

    }#loop through rows

    #clean up
    $sw.Close();
    $dr.Close();
} # bcp-data