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This library adds basic support for "Upsert" operations to EF Core.

Uses INSERT … ON CONFLICT DO UPDATE in PostgreSQL/Sqlite, MERGE in SqlServer and INSERT INTO … ON DUPLICATE KEY UPDATE in MySQL.

Also supports injecting sql command runners to add support for other providers

A typical upsert command could look something like this:

DataContext.DailyVisits
    .Upsert(new DailyVisit
    {
        UserID = userID,
        Date = DateTime.UtcNow.Date,
        Visits = 1,
    })
    .On(v => new { v.UserID, v.Date })
    .WhenMatched(v => new DailyVisit
    {
        Visits = v.Visits + 1,
    })
    .RunAsync();

In this case, the upsert command will ensure that a new DailyVisit will be added to the database. If a visit with the same UserID and Date already exists, it will be updated by incrementing it's Visits value by 1.

Please read our Usage page for more examples