TestSqlConnections.ps1

$Server = 'SQL-APPS'
$ConnectionTimeout = 15
$MaxConnections = 500

$ConnectionStringFormat = 'Server = {0}; Connection Timeout = {1}; Max Pool Size = {2}; Integrated Security = True;'
$CommandQuery = 'SELECT 1'

$ConnectionString = $ConnectionStringFormat -f $Server, $ConnectionTimeout, $MaxConnections
$Connections = [System.Collections.ArrayList] @()

for ($I = 0; $I -lt $MaxConnections; $I++)
{
    [Void] $Connections.Add([System.Data.SqlClient.SqlConnection]::new($ConnectionString))
}

for ($I = 0; $I -lt $Connections.Count; $I++)
{
    $Connection = $Connections[$I]
    try
    {
        Write-Verbose "Open connection #$I." -Verbose

        $Connection.Open()

        $Command = [System.Data.SqlClient.SqlCommand]::new($CommandQuery, $Connection)

        try
        {
            $Adapter = [System.Data.SqlClient.SqlDataAdapter]::new()
            $Adapter.SelectCommand = $Command

            try
            {
                $DataSet = [System.Data.DataSet]::new()

                try
                {
                    Write-Verbose "Invoke query." -Verbose

                    [Void] $Adapter.Fill($DataSet)
                }
                finally
                {
                    $DataSet.Dispose()
                }
            }
            finally
            {
                $Adapter.Dispose()
            }
        }
        finally
        {
            $Command.Dispose()
        }
    }
    catch
    {
        $_ | Write-Error
        break
    }
}

Read-Host -Prompt 'Press Enter to close all connections'

for ($I = 0; $I -lt $Connections.Count; $I++)
{
    $Connection = $Connections[$I]
    if ($Connection)
    {
        if ($Connection.State -eq [System.Data.ConnectionState]::Open)
        {
            Write-Verbose "Close connection #$I." -Verbose

            $Connection.Close()
            [System.Data.SqlClient.SqlConnection]::ClearPool($Connection)
        }
        $Connection.Dispose()
    }
}