docs-v2/content/influxdb3/cloud-serverless/query-data/influxql/basic-query.md

213 lines
7.8 KiB
Markdown

---
title: Perform a basic InfluxQL query
seotitle: Perform a basic InfluxQL query in InfluxDB Cloud
description: >
A basic InfluxQL query that queries data from InfluxDB most commonly includes
`SELECT`, `FROM`, and `WHERE` clauses.
menu:
influxdb3_cloud_serverless:
name: Basic query
parent: Query with InfluxQL
identifier: query-influxql-basic
weight: 202
influxdb3/cloud-serverless/tags: [query, influxql]
list_code_example: |
```sql
SELECT temp, room FROM home WHERE time >= now() - 1d
```
---
InfluxQL (Influx Query Language) is an SQL-like query language used to interact
with InfluxDB and work with times series data.
A basic InfluxQL query that queries data from InfluxDB most commonly includes the
following clauses:
{{< req type="key" >}}
- {{< req "\*">}} `SELECT`: Specify fields, tags, and calculations to return from a
measurement or use the wildcard alias (`*`) to select all fields and tags
from a measurement. It requires at least one
[field key](/influxdb3/cloud-serverless/reference/glossary/#field-key) or the wildcard alias (`*`).
For more information, see [Notable SELECT statement behaviors](/influxdb3/cloud-serverless/reference/influxql/select/#notable-select-statement-behaviors).
- {{< req "\*">}} `FROM`: Specify the [measurement](/influxdb3/cloud-serverless/reference/glossary/#measurement) to query from.
It requires one or more comma-delimited [measurement expressions](/influxdb3/cloud-serverless/reference/influxql/select/#measurement_expression).
- `WHERE`: Filter data based on
[field values](/influxdb3/cloud-serverless/reference/glossary/#field),
[tag values](/influxdb3/cloud-serverless/reference/glossary/#tag), or
[timestamps](/influxdb3/cloud-serverless/reference/glossary/#timestamp). Only return data that meets the specified conditions--for example, falls within
a time range, contains specific tag values, or contains a field value outside a specified range.
{{% influxdb/custom-timestamps %}}
```sql
SELECT
temp,
hum,
room
FROM home
WHERE
time >= '2022-01-01T08:00:00Z'
AND time <= '2022-01-01T20:00:00Z'
```
{{% /influxdb/custom-timestamps %}}
## Result set
If at least one row satisfies the query, {{% product-name %}} returns row data in the query result set.
If a query uses a `GROUP BY` clause, the result set includes the following:
- Columns listed in the query's `SELECT` clause
- A `time` column that contains the timestamp for the record or the group
- An `iox::measurement` column that contains the record's measurement (table) name
- Columns listed in the query's `GROUP BY` clause; each row in the result set contains the values used for grouping
### GROUP BY result columns
If a query uses `GROUP BY` and the `WHERE` clause doesn't filter by time, then groups are based on the [default time range](/influxdb3/cloud-serverless/reference/influxql/group-by/#default-time-range).
## Basic query examples
- [Query data within time boundaries](#query-data-within-time-boundaries)
- [Query data without time boundaries](#query-data-without-time-boundaries)
- [Query specific fields and tags](#query-specific-fields-and-tags)
- [Query fields based on tag values](#query-fields-based-on-tag-values)
- [Query points based on field values](#query-points-based-on-field-values)
- [Alias queried fields and tags](#alias-queried-fields-and-tags)
> [!Note]
> #### Sample data
>
> The following examples use the
> [Get started home sensor data](/influxdb3/cloud-serverless/reference/sample-data/#get-started-home-sensor-data).
> To run the example queries and return results,
> [write the sample data](/influxdb3/cloud-serverless/reference/sample-data/#write-the-home-sensor-data-to-influxdb)
> to your {{% product-name %}} database before running the example queries.
### Query data within time boundaries
- Use the `SELECT` clause to specify what tags and fields to return.
Specify at least one field key.
To return all tags and fields, use the wildcard alias (`*`).
- Specify the measurement to query in the `FROM` clause.
- Specify time boundaries in the `WHERE` clause.
Include time-based predicates that compare the value of the `time` column to a timestamp.
Use the `AND` logical operator to chain multiple predicates together.
{{% influxdb/custom-timestamps %}}
```sql
SELECT *
FROM home
WHERE
time >= '2022-01-01T08:00:00Z'
AND time <= '2022-01-01T12:00:00Z'
```
{{% /influxdb/custom-timestamps %}}
Query time boundaries can be relative or absolute.
{{< expand-wrapper >}}
{{% expand "Query with relative time boundaries" %}}
To query data from relative time boundaries, compare the value of the `time`
column to a timestamp calculated by subtracting an interval from a timestamp.
Use `now()` to return the timestamp for the current time (UTC).
##### Query all data from the last month
```sql
SELECT * FROM home WHERE time >= now() - 30d
```
##### Query one day of data data from a week ago
```sql
SELECT *
FROM home
WHERE
time >= now() - 7d
AND time <= now() - 6d
```
{{% /expand %}}
{{% expand "Query with absolute time boundaries" %}}
To query data from absolute time boundaries, compare the value of the `time` column
to a timestamp literal.
Use the `AND` logical operator to chain together multiple predicates and define
both start and stop boundaries for the query.
{{% influxdb/custom-timestamps %}}
```sql
SELECT
*
FROM
home
WHERE
time >= '2022-01-01T08:00:00Z'
AND time <= '2022-01-01T20:00:00Z'
```
{{% /influxdb/custom-timestamps %}}
{{% /expand %}}
{{< /expand-wrapper >}}
### Query data without time boundaries
To query data without time boundaries, do not include any time-based predicates
in your `WHERE` clause.
If a time range is not defined in the `WHERE` clause, the default time range is
the Unix epoch (`1970-01-01T00:00:00Z`) to _now_.
> [!Warning]
> Querying data _without time bounds_ can return an unexpected amount of data.
> The query may take a long time to complete and results may be truncated.
```sql
SELECT * FROM home
```
### Query specific fields and tags
To query specific fields, include them in the `SELECT` clause.
If querying multiple fields or tags, comma-delimit each.
If a field or tag key includes special characters or spaces or is case-sensitive,
wrap the key in _double-quotes_.
```sql
SELECT time, room, temp, hum FROM home
```
### Query fields based on tag values
- In the `SELECT` clause, include fields you want to query and tags you want to base conditions on.
- In the `WHERE` clause, include predicates that compare the tag identifier to a string literal.
Use [logical operators](/influxdb3/cloud-serverless/reference/influxql/where/#logical-operators) to chain multiple predicates together and apply
multiple conditions.
```sql
SELECT * FROM home WHERE room = 'Kitchen'
```
### Query points based on field values
- In the `SELECT` clause, include fields you want to query.
- In the `WHERE` clause, include predicates that compare the field identifier to a value or expression.
Use [logical operators](/influxdb3/cloud-serverless/reference/influxql/where/#logical-operators) (`AND`, `OR`) to chain multiple predicates together
and apply multiple conditions.
```sql
SELECT co, time FROM home WHERE co >= 10 OR co <= -10
```
### Alias queried fields and tags
To alias or rename fields and tags that you query, use the `AS` clause.
After the tag, field, or expression you want to alias, pass `AS` followed by the alias name as an identifier (wrap in double quotes (`"`) if the alias includes spaces or special characters)--for example:
```sql
SELECT temp AS temperature, hum AS "humidity (%)" FROM home
```
> [!Note]
> When aliasing columns in **InfluxQL**, use the `AS` clause and an [identifier](/influxdb3/cloud-serverless/reference/influxql/#identifiers).
> When [aliasing columns in **SQL**](/influxdb3/cloud-serverless/query-data/sql/basic-query/#alias-queried-fields-and-tags), you can use the `AS` clause to define the alias, but it isn't necessary.