# Dapper for reads. Bulk for writes. Dapper is excellent at reading data. It is not a bulk writer. The usual workaround — a loop of `INSERT` / `UPDATE` / `DELETE` — costs one round-trip per row and gets slow as soon as the set grows. **ETLBox.DbExtensions** adds `BulkInsert`, `BulkUpdate`, `BulkDelete`, and `BulkMerge` to the same connection. One extra `using`. No new client. If the class you already use is `SqlBulkCopy`, see [Beyond SqlBulkCopy](/sqlbulkcopy/). **Still writing this?** ```csharp foreach (var customer in customers) connection.Execute( "INSERT INTO Customer (Id, Name, City) VALUES (@Id, @Name, @City)", customer); ``` **One call instead — and much faster** ```csharp connection.BulkInsert(customers); ``` The second snippet is not just shorter. On SQL Server, 5,000 inserts took **8 seconds** with the loop and **70 ms** with `BulkInsert()` — about **110×** faster. Update, delete, and merge follow the same pattern.

Dapper loop vs SqlBulkCopy vs DbExtensions

DbExtensions does not replace Dapper, and it does not pretend SqlBulkCopy is slow. It covers the write operations Dapper never added — on more than SQL Server.

DbExtensions

One line, many databases

Same IDbConnection as Dapper
Insert, update, delete, merge
Your POCOs — no DataTable
SQL Server, Postgres, MySQL, Oracle, SQLite, …
Same bulk engine as ETLBox data flows

One round-trip per row

Great for queries, not for bulk writes
foreach + Execute does not scale
Merge becomes select-then-insert-or-update
SqlBulkCopy is insert-only, SQL Server only
A second client is more than you asked for

SQL Server, 5,000 rows

Measured with the open benchmark in etlbox.demo. Read the table as order of magnitude, not a guarantee.

	Dapper loop	SqlBulkCopy	DbExtensions
Insert	{{< compare-cell no "7.9 s — one round-trip per row" >}}	{{< compare-cell yes "20 ms — SQL Server only" >}}	{{< compare-cell yes "70 ms — POCOs, many databases" >}}
Update / delete	{{< compare-cell no "Same loop, ~7.5 s" >}}	{{< compare-cell no "Not included" >}}	{{< compare-cell yes "BulkUpdate / BulkDelete" >}}
Upsert / sync	{{< compare-cell no "Select + insert or update, 11.6 s" >}}	{{< compare-cell no "Not included" >}}	{{< compare-cell yes "BulkMerge — 0.28 s" >}}
API	{{< compare-cell no "SQL you already write, row by row" >}}	{{< compare-cell no "DataTable + column maps" >}}	{{< compare-cell yes "Your POCOs on IDbConnection" >}}

Method, script, and caveats: how we measured this.

## Insert, update, delete, merge Same connection as Dapper. One method each — not a new client. {{< tabs "dbext-ops" >}} {{< tab "Bulk Insert" >}} ```C# using ETLBox.DbExtensions; var connection = new SqlConnection("your-connection-string"); var customers = Enumerable.Range(1, 10_000) .Select(i => new Customer { Id = i, Name = $"Name {i}", City = $"City {i % 50}" }); connection.BulkInsert(customers); public class Customer { public int Id { get; set; } public string Name { get; set; } public string City { get; set; } } ``` {{< /tab >}} {{< tab "Bulk Merge" >}} ```C# using ETLBox.DbExtensions; var connection = new SqlConnection("your-connection-string"); var customers = Enumerable.Range(1, 10_000) .Select(i => new Customer { Id = i, Name = $"Customer {i}", City = "Merged City" }); connection.BulkMerge(customers, options => { options.MergeMode = MergeMode.Full; }); public class Customer : MergeableRow { [IdColumn] public int Id { get; set; } public string Name { get; set; } public string City { get; set; } } ``` {{< /tab >}} {{< tab "Bulk Update" >}} ```C# using ETLBox.DbExtensions; var connection = new SqlConnection("your-connection-string"); var customers = Enumerable.Range(1, 10_000) .Select(i => new Customer { Id = i, Name = $"Updated {i}" }); connection.BulkUpdate(customers); public class Customer { [IdColumn] public int Id { get; set; } public string Name { get; set; } public string City { get; set; } } ``` {{< /tab >}} {{< tab "Bulk Delete" >}} ```C# using ETLBox.DbExtensions; var connection = new SqlConnection("your-connection-string"); var customers = Enumerable.Range(1, 10_000) .Select(i => new Customer { Id = i }); connection.BulkDelete(customers); public class Customer { [IdColumn] public int Id { get; set; } } ``` {{< /tab >}} {{< /tabs >}}

Try DbExtensions

Keep Dapper. Add bulk writes.

The product site has the docs, the trial, and pricing. NuGet without a key is limited to 5,000 rows. A trial key removes the limit for 45 days.

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