Conflict Inserts

Use conflict-aware insert conveniences when inserts should ignore or update rows that already match a conflict target.

csharp

db.InsertOrIgnore(user, table: "users_staging")
    .OnConflict(u => u.Email)
    .Execute();

db.InsertOrUpdate(user)
    .OnConflict(u => u.Email)
    .Update(u => u.Name, u => u.UpdatedAt)
    .Execute();

Many variants use the same API shape:

csharp

db.InsertOrUpdateMany(users, table: "users_2026")
    .OnConflict(u => u.Email)
    .Update(u => u.Name, u => u.UpdatedAt)
    .Execute();

Available methods:

InsertOrIgnore(entity)
InsertOrIgnore(entity, table)
InsertOrIgnoreMany(entities)
InsertOrIgnoreMany(entities, table)
InsertOrUpdate(entity)
InsertOrUpdate(entity, table)
InsertOrUpdateMany(entities)
InsertOrUpdateMany(entities, table)

OnConflict(...) uses mapped CLR member selectors for the conflict target. InsertOrUpdate and InsertOrUpdateMany use Update(...) to choose mapped columns updated on conflict.

When OnConflict(...) is omitted, Db4Net uses key metadata as the default conflict target. Conflict-aware inserts can use composite [Key] metadata as the default target. This requires non-database-generated key columns; an identity key such as [Key] plus [DatabaseGenerated(DatabaseGeneratedOption.Identity)] is still valid for entity update/delete predicates, but it is not a valid conflict target.

Conflict-aware insert terminals return affected row counts. Generated-key readback is intentionally limited to regular single-row InsertInto<T>() / Insert(entity) commands.

WARNING

Database-generated mapped members cannot be used as default or explicit conflict targets, and cannot be selected through InsertOrUpdate.Update(...). Columns selected in OnConflict(...) also cannot be selected through InsertOrUpdate.Update(...).

Dialect differences

SQLite and PostgreSQL render native ON CONFLICT. MySQL renders INSERT IGNORE for InsertOrIgnore(...) and ON DUPLICATE KEY UPDATE for InsertOrUpdate(...); duplicate-key handling applies to any primary or unique key violation, and INSERT IGNORE can also turn some data errors into warnings according to MySQL rules. SQL Server renders MERGE ... WITH (HOLDLOCK). See Conflict Inserts in the dialect guide.

Conflict Inserts ​

Conflict Inserts