https://learn.microsoft.com/en-us/dotnet/api/system.data.sqlclient.sqlbulkcopycolumnmappingcollection.indexof?view=netframework-4.8.1
SqlBulkCopyColumnMappingCollection.IndexOf(SqlBulkCopyColumnMapping) Method (System.Data.SqlClient)...
Gets the index of the specified SqlBulkCopyColumnMapping object.
system dataindexofmethod