function Invoke-DbUpdateScript {
	[CmdletBinding()]
	param(
		[Parameter(Mandatory = $true, ValueFromPipelineByPropertyName = $true)]
		[string] $Database,
		[Parameter(ValueFromPipelineByPropertyName = $true)]
		[string] $Port = "1433",
		[Parameter(Mandatory = $true, ValueFromPipelineByPropertyName = $true, ParameterSetName = "Script")]
		[string] $Script,
		[Parameter(Mandatory = $true, ValueFromPipelineByPropertyName = $true, ParameterSetName = "Sql")]
		[string] $Sql,
		[Parameter(Mandatory = $true, ValueFromPipelineByPropertyName = $true)]
		[ValidateSet("Dev","Test","Prod")]
		[string] $Environment,
		[Parameter(ValueFromPipelineByPropertyName = $true)]
		[string] $ComputerName = $env:COMPUTERNAME,
		[Parameter(ValueFromPipelineByPropertyName = $true)]
		[System.Management.Automation.PSCredential] $Credential,
		[Parameter(ValueFromPipelineByPropertyName = $true)]
		[System.Management.Automation.Runspaces.AuthenticationMechanism] $Authentication,
		[Parameter(ValueFromPipelineByPropertyName = $true)]
		[switch] $Throw,
		[switch] $SurpressWriteHost
	)

	if($PSCmdlet.ParameterSetName -eq "Script") {
		$path = Get-DbUpdateScriptPath -Database $Database -Script $Script -Environment Staging

		if((Test-Path -Path $path) -eq $false) {
			throw (
				"Invoke-DbUpdateScript: Script '{0}' not found at '{1}'. Please ensure it exists and try again." -f `
				$Script, $path
			)
		}

		$Sql = Get-Content -Path $path -Raw
	}

	$dbhost = Get-DbConnectionString -Database $Database -Port $Port -Environment $Environment

	$scriptBlock = {
		param([string] $dbhost, [string] $database, [string] $sql, [bool] $SurpressWriteHost)

		$tempfile = New-TemporaryFile
		$sql | Set-Content -Path $tempfile -Force

		$errorfile = New-TemporaryFile

		if(-not $SurpressWriteHost) {
			Write-Host @"

----------------
dbhost: $dbhost
database: $database
tempfile: $tempfile
errorfile: $errorfile
sql:
$sql
----------------

"@
		}

		$cmd = 'sqlcmd -E -I -S "{0}" -d "{1}" -i "{2}"' -f $dbhost, $database, $tempfile
		#$cmd = 'sqlcmd -E -I -S "{0}" -d "{1}" -Q "{2}"' -f $dbhost, $database, $sql

		$result = invoke-expression "$cmd 2> $errorfile"

		$errorc = Get-Content -Path $errorfile -Raw
		if($errorc.length -gt 0) {
			if($result.length -gt 0) { $result += "`r`n`r`n" }
			$result += $errorc
		}

		Remove-Item -Path $tempfile | Out-Null
		Remove-Item -Path $errorfile | Out-Null

		return $result
	}

	if($Credential -eq $null) {
		if(-not $SurpressWriteHost) {
			Write-Host ("Executing script on {0}. (script path = '{1}')" -f $dbhost, $path)
		}

		$output = Invoke-Command `
					-ScriptBlock $scriptBlock `
					-ArgumentList @($dbhost, $Database, $Sql, $SurpressWriteHost)

	} else {
		if(-not $SurpressWriteHost) {
			Write-Host (
				"Executing script on {0} with credentials for '{1}'. (script path = '{2}')" -f `
				$dbhost, $Credential.UserName, $path
			)
		}

		$output = Invoke-Command `
					-ComputerName $ComputerName -ScriptBlock $scriptBlock `
					-Credential $Credential -Authentication $Authentication `
					-ArgumentList @($dbhost, $Database, $Sql, $SurpressWriteHost)
	}


	## no error or output to report

	if([string]::IsNullOrWhiteSpace($output)) {
		return $null
	}


	## Error processing

	$errors = Convert-DbUpdateOutputToErrors -Output $output

	if(@($errors).Count -gt 0) {
		# This is used in debugging locally
		if(-not $SurpressWriteHost) {
			Write-Host @"

------------- ERRORS --------------
"@

			if($output -match "sqlcmd \:") {
				Write-Host @"
$output
-----------------------------------

"@
			}
		}

		if($Throw) {
			$message = [System.Text.StringBuilder]::new(100 * $errors.Count)
			foreach($er in $errors) {
				if($message.Length -gt 0) { $message.AppendLine() }
				$message.Append($er.OriginalErrorMessage)
			}
			throw $message.ToString()
		}
	}

	return $output
}