index.md

---
title: TDengine SQL
description: "The syntax supported by TDengine SQL "
---

This section explains the syntax to operating databases, tables, STables, inserting data, selecting data, functions and some tips that can be used in TDengine SQL. It would be easier to understand with some fundamental knowledge of SQL.

TDengine SQL is the major interface for users to write data into or query from TDengine. For users to easily use, syntax similar to standard SQL is provided. However, please note that TDengine SQL is not standard SQL. For instance, TDengine doesn't provide the functionality of deleting time series data, thus corresponding statements are not provided in TDengine SQL.

TDengine SQL doesn't support abbreviation for keywords, for example `DESCRIBE` can't be abbreviated as `DESC`.

Syntax Specifications used in this chapter:

- The content inside <\> needs to be input by the user, excluding <\> itself.
- \[ \] means optional input, excluding [] itself.
- | means one of a few options, excluding | itself.
- … means the item prior to it can be repeated multiple times.

To better demonstrate the syntax, usage and rules of TAOS SQL, hereinafter it's assumed that there is a data set of meters. Assuming each meter collects 3 data measurements: current, voltage, phase. The data model is shown below:

```sql
taos> DESCRIBE meters;
             Field              |        Type        |   Length    |    Note    |
=================================================================================
 ts                             | TIMESTAMP          |           8 |            |
 current                        | FLOAT              |           4 |            |
 voltage                        | INT                |           4 |            |
 phase                          | FLOAT              |           4 |            |
 location                       | BINARY             |          64 | TAG        |
 groupid                        | INT                |           4 | TAG        |
```

The data set includes the data collected by 4 meters, the corresponding table name is d1001, d1002, d1003, d1004 respectively based on the data model of TDengine.