09-csharp.mdx

---
toc_max_heading_level: 4
sidebar_label: C#
title: C# Connector
---

import Tabs from '@theme/Tabs';
import TabItem from '@theme/TabItem';

import Preparition from "./_preparition.mdx"
import CSInsert from "../../07-develop/03-insert-data/_cs_sql.mdx"
import CSInfluxLine from "../../07-develop/03-insert-data/_cs_line.mdx"
import CSOpenTSDBTelnet from "../../07-develop/03-insert-data/_cs_opts_telnet.mdx"
import CSOpenTSDBJson from "../../07-develop/03-insert-data/_cs_opts_json.mdx"
import CSQuery from "../../07-develop/04-query-data/_cs.mdx"
import CSAsyncQuery from "../../07-develop/04-query-data/_cs_async.mdx"

`TDengine.Connector` is a C# language connector provided by TDengine that allows C# developers to develop C# applications that access TDengine cluster data.

The `TDengine.Connector` connector supports connect to TDengine instances via the TDengine client driver (taosc), providing data writing, querying, subscription, schemaless writing, bind interface, etc. The `TDengine.Connector` currently does not provide a REST connection interface. Developers can write their RESTful application by referring to the [REST API](/reference/rest-api/) documentation.

This article describes how to install `TDengine.Connector` in a Linux or Windows environment and connect to TDengine clusters via `TDengine.Connector` to perform basic operations such as data writing and querying.

Note: TDengine Connector 3.x is not compatible with TDengine 2.x. In an environment with TDengine 2.x, you must use TDengine.Connector 1.x for the C# connector.

The source code of `TDengine.Connector` is hosted on [GitHub](https://github.com/taosdata/taos-connector-dotnet/tree/3.0).

## Supported platforms

The supported platforms are the same as those supported by the TDengine client driver.

## Version support

Please refer to [version support list](/reference/connector#version-support)

## Supported features

1. Connection Management
2. General Query
3. Continuous Query
4. Parameter Binding
5. Subscription
6. Schemaless

## Installation Steps

### Pre-installation preparation

* Install the [.NET SDK](https://dotnet.microsoft.com/download)
* [Nuget Client](https://docs.microsoft.com/en-us/nuget/install-nuget-client-tools) (optional installation)
* Install TDengine client driver, please refer to [Install client driver](/reference/connector/#install-client-driver) for details

### Install via dotnet CLI

<Tabs defaultValue="CLI">
<TabItem value="CLI" label="Get C# driver using dotnet CLI">

You can reference the `TDengine.Connector` published in Nuget to the current project via the `dotnet` command under the path of the existing .NET project.

``` bash
dotnet add package TDengine.Connector
```

</TabItem>
<TabItem value="source" label="Use source code to get C# driver">

You can [download the source code](https://github.com/taosdata/taos-connector-dotnet/tree/3.0) and directly reference the latest version of the TDengine.Connector library.

```bash
git clone -b 3.0 https://github.com/taosdata/taos-connector-dotnet.git
cd taos-connector-dotnet
cp -r src/ myProject

cd myProject
dotnet add exmaple.csproj reference src/TDengine.csproj
```
</TabItem>
</Tabs>

## Establish a Connection

``` C#
using TDengineDriver;

namespace TDengineExample
{

    internal class EstablishConnection
    {
        static void Main(String[] args)
        {
            string host = "localhost";
            short port = 6030;
            string username = "root";
            string password = "taosdata";
            string dbname = "";

            var conn = TDengine.Connect(host, username, password, dbname, port);
            if (conn == IntPtr.Zero)
            {
                Console.WriteLine("Connect to TDengine failed");
            }
            else
            {
                Console.WriteLine("Connect to TDengine success");
            }
            TDengine.Close(conn);
            TDengine.Cleanup();
        }
    }
}

```

## Usage examples

### Write data

#### SQL Write

<CSInsert />

#### InfluxDB line protocol write

<CSInfluxLine />

#### OpenTSDB Telnet line protocol write

<CSOpenTSDBTelnet />

#### OpenTSDB JSON line protocol write

<CSOpenTSDBJson />

### Query data

#### Synchronous Query

<CSQuery />

#### Asynchronous query

<CSAsyncQuery />

### More sample programs

|Sample program |Sample program description |
|--------------------------------------------------------------------------------------------------------------------|------------ --------------------------------|
| [CURD](https://github.com/taosdata/taos-connector-dotnet/blob/3.0/examples/Query/Query.cs)                         | Table creation, data insertion, and query examples with TDengine.Connector    |
| [JSON Tag](https://github.com/taosdata/taos-connector-dotnet/blob/3.0/examples/JSONTag)                             | Writing and querying JSON tag data with TDengine Connector |
| [stmt](https://github.com/taosdata/taos-connector-dotnet/tree/3.0/examples/Stmt)                                   | Parameter binding with TDengine Connector |
| [schemaless](https://github.com/taosdata/taos-connector-dotnet/blob/3.0/examples/schemaless)                       | Schemaless writes with TDengine Connector |
| [async query](https://github.com/taosdata/taos-connector-dotnet/blob/3.0/examples/AsyncQuery/QueryAsync.cs) | Asynchronous queries with TDengine Connector |
| [TMQ](https://github.com/taosdata/taos-connector-dotnet/blob/3.0/examples/TMQ/TMQ.cs)      | Data subscription with TDengine Connector |

## Important update records

| TDengine.Connector | Description |
|--------------------|--------------------------------|
|        3.0.0       | Supports TDengine 3.0.0.0. TDengine 2.x is not supported. Added `TDengine.Impl.GetData()` interface to deserialize query results. |
|        1.0.7       | Fixed TDengine.Query() memory leak. |
| 1.0.6 | Fix schemaless bug in 1.0.4 and 1.0.5. |
| 1.0.5 | Fix Windows sync query Chinese error bug. | 1.0.4 | Fix schemaless bug.   |
| 1.0.4 | Add asynchronous query, subscription, and other functions. Fix the binding parameter bug.    |
| 1.0.3 | Add parameter binding, schemaless, JSON tag, etc. |
| 1.0.2 | Add connection management, synchronous query, error messages, etc.   |

## Other descriptions

### Third-party driver

`Taos` is an ADO.NET connector for TDengine, supporting Linux and Windows platforms. Community contributor `Maikebing@@maikebing contributes the connector`. Please refer to:

* Interface download:<https://github.com/maikebing/Maikebing.EntityFrameworkCore.Taos>
* Usage notes:<https://www.taosdata.com/blog/2020/11/02/1901.html>

## Frequently Asked Questions

1. "Unable to establish connection", "Unable to resolve FQDN"

  Usually, it's caused by an incorrect FQDN configuration. Please refer to this section in the [FAQ](https://docs.tdengine.com/2.4/train-faq/faq/#2-how-to-handle-unable-to-establish-connection) to troubleshoot.

2. Unhandled exception. System.DllNotFoundException: Unable to load DLL 'taos' or one of its dependencies: The specified module cannot be found.

  This is usually because the program did not find the dependent client driver. The solution is to copy `C:\TDengine\driver\taos.dll` to the `C:\Windows\System32\` directory on Windows, and create the following soft link on Linux `ln -s /usr/local/taos/driver/libtaos.so.x.x .x.x /usr/lib/libtaos.so` will work.

## API Reference

[API Reference](https://docs.taosdata.com/api/connector-csharp/html/860d2ac1-dd52-39c9-e460-0829c4e5a40b.htm)