Entity framework core, code first migration with data migration

Question

I am trying to use EF Core code first migrations to de-normalise an existing table.

I have en existing table LoginEvent which data looks like this:

Answer 1

You can execute any SQL using migrationBuilder.Sql(theSqlString).

In your case

migrationBuilder.Sql("INSERT INTO Venue SELECT DISTINCT VenueRef, VenueName FROM LoginEvent");

Run this in the migration after creating the new table Venue and before dropping the old column VenueName.

See also Custom Migrations Operations.