CODEWITHSUNDEEP
powershelltype-conversionpowershell-2.0
Travis Parks
Travis Parks

Reputation: 8695

PowerShell Converting $null into 0

I have a pretty straight-forward function for grabbing SQL results: 

function RunSqlCommand($sql)
{
    $connection = $null
    $command = $null
    try
    {
        $connectionString = "data source=localhost; integrated security=true"
        $connection = New-Object System.Data.SqlClient.SqlConnection($connectionString)
        $command = $connection.CreateCommand()
        $command.CommandText = $sql
        $adapter = New-Object System.Data.SqlClient.SqlDataAdapter($command)
        $dataSet = New-Object System.Data.DataSet
        $adapter.Fill($dataSet)
        $results = $dataSet.Tables | Select-Object -ExpandProperty "Rows"
        return $results
    }
    finally
    {
        if ($command -ne $null) { $command.Dispose() }
        if ($connection -ne $null) { $connection.Dispose() }
    }
}

Whenever there are no results, the $results variable is $null. However, when I inspect the return value in the calling method, it magically becomes 0.

Is PowerShell doing something behind the scenes? I really do want to return $null to represent "no results".

Upvotes: 0

Views: 694

Answers (1)

Mike Shepard
Mike Shepard

Reputation: 18146

$adapter.Fill() returns the number of rows added or refreshed in the dataset.

To fix, you can do this:

[void]$adapter.Fill($dataSet)

or 

$adapter.Fill($dataset) | out-null

Upvotes: 1

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