let
Source = Table.FromColumns(
{
{123, 34, 12, "txt", null},
{123, "txt", 34, 12, null},
{"txt", 123, 34, 12, null},
{123, "txt", "34", 12, null}
}
),
ChType = Table.TransformColumnTypes( Source,
{
{"Column1", Int64.Type},
{"Column2", Int64.Type},
{"Column3", Int64.Type},
{"Column4", Int64.Type}
}
)
in
ChType