TDengine provides the functionality of deleting data from a table or STable according to specified time range, it can be used to cleanup abnormal data generated due to device failure. Please be noted that this functionality is only available in Enterprise version, please refer to [TDengine Enterprise Edition](https://tdengine.com/products#enterprise-edition-link)
**Syntax:**
```sql
DELETE FROM [ db_name. ] tb_name [WHERE condition];
```
**Description:** Delete data from a table or STable
**Parameters:**
- `db_name`: Optional parameter, specifies the database in which the table exists; if not specified, the current database will be used.
- `tb_name`: Mandatory parameter, specifies the table name from which data will be deleted, it can be normal table, subtable or STable.
- `condition`: Optional parameter, specifies the data filter condition. If no condition is specified all data will be deleted, so please be cautions to delete data without any condition. The condition used here is only applicable to the first column, i.e. the timestamp column. If the table is a STable, the condition is also applicable to tag columns.
**More Explanations:**
The data can't be recovered once deleted, so please be cautious to use the functionality of deleting data. It's better to firstly make sure the data to be deleted using `select` then execute `delete`.
**Example:**
`meters` is a STable, in which `groupid` is a tag column of int type. Now we want to delete the data older than 2021-10-01 10:40:00.100 and `groupid` is 1. The SQL for this purpose is like below:
```sql
delete from meters where ts < '2021-10-01 10:40:00.100' and groupid=1 ;
```
The output is:
```
Deleted 102000 row(s) from 1020 table(s) (0.421950s)
```
It means totally 102,000 rows of data have been deleted from 1,020 sub tables.
* Install TDengine client driver, please refer to [Install client driver](/reference/connector#Install client driver) for details
* Install TDengine client driver, please refer to [Install client driver](/reference/connector/#install-client-driver) for details
### Install via dotnet CLI
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@@ -57,7 +57,7 @@ Please refer to [version support list](/reference/connector#version-support)
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.
This API is created successfully without checking permissions, but only when you execute a Query or Exec, and check if user/password/host/port is legal.
2. specify the firstEp and the secondEp in the configuration file taos.cfg
```shell
# first fully qualified domain name (FQDN) for TDengine system
firstEp cluster_node1:6030
```shell
# first fully qualified domain name (FQDN) for TDengine system
firstEp cluster_node1:6030
# second fully qualified domain name (FQDN) for TDengine system, for cluster only
secondEp cluster_node2:6030
# second fully qualified domain name (FQDN) for TDengine system, for cluster only
secondEp cluster_node2:6030
# default system charset
# charset UTF-8
# default system charset
# charset UTF-8
# system locale
# locale en_US.UTF-8
```
# system locale
# locale en_US.UTF-8
```
In the above example, JDBC uses the client's configuration file to establish a connection to a hostname `cluster_node1`, port 6030, and a database named `test`. When the firstEp node in the cluster fails, JDBC attempts to connect to the cluster using secondEp.
In TDengine, as long as one node in firstEp and secondEp is valid, the connection to the cluster can be established normally.
> **Note**: The configuration file here refers to the configuration file on the machine where the application that calls the JDBC Connector is located, the default path is `/etc/taos/taos.cfg` on Linux, and the default path is `C://TDengine/cfg/taos.cfg` on Windows.
:::note
The configuration file here refers to the configuration file on the machine where the application that calls the JDBC Connector is located, the default path is `/etc/taos/taos.cfg` on Linux, and the default path is `C://TDengine/cfg/taos.cfg` on Windows.
