Entity Framework Extensions Column PrimaryKey Expression

The ColumnPrimaryKeyExpression allows you to choose a specific property or properties as a key to perform the bulk operations.

The following example uses Login and Password properties as a key to perform BulkMerge.

using (var context = new EntityContext())
        options => options.ColumnPrimaryKeyExpression = customer => new 

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It will update those records for which the Login and Password already exists in the database and all the new records will be inserted to the database.