---
title: SELECT statement
description: Use the SELECT statement to query data from a particular measurement or measurements.
url: https://docs.influxdata.com/influxdb/cloud/query-data/influxql/explore-data/select/
estimated_tokens: 12526
product: InfluxDB Cloud (TSM)
version: cloud
---

# SELECT statement

Use the `SELECT` statement to query data from a particular [measurement](/influxdb/cloud/reference/glossary/#measurement) or measurements.

-   [Syntax](#syntax)
-   [Examples](#examples)
-   [Common issues](#common-issues-with-the-select-statement)
-   [Regular expressions](#regular-expressions)
-   [Data types and cast operations](#data-types-and-cast-operations)
-   [Merge behavior](#merge-behavior)
-   [Multiple statements](#multiple-statements)

## Syntax

```sql
SELECT <field_key>[,<field_key>,<tag_key>] FROM <measurement_name>[,<measurement_name>]
```

**Note:** The `SELECT` statement **requires** a `SELECT` clause and a `FROM` clause.

### `SELECT` clause

The `SELECT` clause supports several formats for specifying data:

-   `SELECT *` - Returns all [fields](/influxdb/cloud/reference/glossary/#field) and [tags](/influxdb/cloud/reference/glossary/#tag).
-   `SELECT "<field_key>"` - Returns a specific field.
-   `SELECT "<field_key>","<field_key>"` - Returns more than one field.
-   `SELECT "<field_key>","<tag_key>"` - Returns a specific field and tag. The `SELECT` clause must specify at least one field when it includes a tag.
-   `SELECT "<field_key>"::field,"<tag_key>"::tag` - Returns a specific field and tag. The `::[field | tag]` syntax specifies the [identifier’s](/influxdb/cloud/reference/syntax/influxql/spec/#identifiers) type. Use this syntax to differentiate between field keys and tag keys with the same name.

Other supported features include:

-   [Functions](/influxdb/cloud/query-data/influxql/functions/)
-   [Basic cast operations](#data-types-and-cast-operations)
-   [Regular expressions](/influxdb/cloud/query-data/influxql/explore-data/regular-expressions/)

**Note:** The SELECT statement cannot include an aggregate function **and** a non-aggregate function, field key, or tag key. For more information, see [error about mixing aggregate and non-aggregate queries](/enterprise_influxdb/v1/troubleshooting/errors/#error-parsing-query-mixing-aggregate-and-non-aggregate-queries-is-not-supported).

### `FROM` clause

The `SELECT` clause specifies the measurement to query. This clause supports several formats for specifying a [measurement](/influxdb/cloud/reference/glossary/#measurement):

-   `FROM <measurement_name>` - Returns data from a measurement.
-   `FROM <measurement_name>,<measurement_name>` - Returns data from more than one measurement.
-   `FROM <database_name>.<retention_policy_name>.<measurement_name>` - Returns data from a fully qualified measurement.
-   `FROM <database_name>..<measurement_name>` - Returns data from a measurement.

#### Quoting

[Identifiers](/influxdb/cloud/reference/syntax/influxql/spec/#identifiers) **must** be double quoted if they contain characters other than `[A-z,0-9,_]`, begin with a digit, or are an [InfluxQL keyword](https://github.com/influxdata/influxql/blob/master/README.md#keywords). While not always necessary, we recommend that you double quote identifiers.

**Note:** InfluxQL quoting guidelines differ from [line protocol quoting guidelines](/influxdb/cloud/reference/syntax/line-protocol/#quotes). Please review the [rules for single and double-quoting](/influxdb/cloud/reference/syntax/line-protocol/#quotes) in queries.

### Examples

[](#select-all-fields-and-tags-from-a-measurement)

Select all fields and tags from a measurement

```sql
SELECT * FROM "h2o_feet"
```

Output:

Name: h2o\_feet

| time | level description | location | water_level |
| --- | --- | --- | --- |
| 2019-08-17T00:00:00Z | below 3 feet | santa_monica | 2.0640000000 |
| 2019-08-17T00:00:00Z | between 6 and 9 feet | coyote_creek | 8.1200000000 |
| 2019-08-17T00:06:00Z | below 3 feet | santa_monica | 2.1160000000 |
| 2019- 08-17T00:06:00Z | between 6 and 9 feet | coyote_creek | 8.0050000000 |
| 2019-08-17T00:12:00Z | below 3 feet | santa_monica | 2.0280000000 |
| 2019-08-17T00:12:00Z | between 6 and 9 feet | coyote_creek | 7.8870000000 |
| 2019-08-17T00:18:00Z | below 3 feet | santa_monica | 2.1260000000 |

The data above is a partial listing of the query output, as the result set is quite large. The query selects all [fields](/influxdb/cloud/reference/glossary/#field) and [tags](/influxdb/cloud/reference/glossary/#tag) from the `h2o_feet` [measurement](/influxdb/cloud/reference/glossary/#measurement).

[](#select-specific-tags-and-fields-from-a-measurement)

Select specific tags and fields from a measurement

```sql
SELECT "level description","location","water_level" FROM "h2o_feet"
```

Output:

Name: h2o\_feet

| time | level description | location | water_level |
| --- | --- | --- | --- |
| 2019-08-17T00:00:00Z | below 3 feet | santa_monica | 2.0640000000 |
| 2019-08-17T00:00:00Z | between 6 and 9 feet | coyote_creek | 8.1200000000 |

The query selects the `level description` field, the `location` tag, and the `water_level` field.

**Note:** The `SELECT` clause must specify at least one field when it includes a tag.

[](#select-specific-tags-and-fields-from-a-measurement-and-provide-their-identifier-type)

Select specific tags and fields from a measurement and provide their identifier type

```sql
SELECT "level description"::field,"location"::tag,"water_level"::field FROM "h2o_feet"
```

Output:

Name: h2o\_feet

| time | level description | location | water_level |
| --- | --- | --- | --- |
| 2019-08-17T00:24:00Z | between 6 and 9 feet | coyote_creek | 7.6350000000 |
| 2019-08-17T00:30:00Z | below 3 feet | santa_monica | 2.0510000000 |
| 2019-08-17T00:30:00Z | between 6 and 9 feet | coyote_creek | 7.5000000000 |
| 2019-08-17T00:36:00Z | below 3 feet | santa_monica | 2.0670000000 |
| 2019-08-17T00:36:00Z | between 6 and 9 feet | coyote_creek | 7.3720000000 |
| 2019-08-17T00:42:00Z | below 3 feet | santa_monica | 2.0570000000 |

The query selects the `level description` field, the `location` tag, and the `water_level` field from the `h2o_feet` measurement. The `::[field | tag]` syntax specifies if the [identifier](/influxdb/cloud/reference/syntax/influxql/spec/#identifiers) is a field or tag. Use `::[field | tag]` to differentiate between [an identical field key and tag key](/v2.4/reference/faq/#how-do-i-query-data-with-an-identical-tag-key-and-field-key) . That syntax is not required for most use cases.

[](#select-all-fields-from-a-measurement)

Select all fields from a measurement

```sql
SELECT *::field FROM "h2o_feet"
```

Output:

Name: h2o\_feet

| time | level description | water_level |
| --- | --- | --- |
| 2019-08-17T00:00:00Z | below 3 feet | 2.0640000000 |
| 2019-08-17T00:00:00Z | between 6 and 9 feet | 8.1200000000 |
| 2019-08-17T00:06:00Z | below 3 feet | 2.1160000000 |
| 2019-08-17T00:06:00Z | between 6 and 9 feet | 8.0050000000 |
| 2019-08-17T00:12:00Z | below 3 feet | 2.0280000000 |
| 2019-08-17T00:12:00Z | between 6 and 9 feet | 7.8870000000 |

The query selects all fields from the `h2o_feet` measurement. The `SELECT` clause supports combining the `*` syntax with the `::` syntax.

[](#select-a-specific-field-from-a-measurement-and-perform-basic-arithmetic)

Select a specific field from a measurement and perform basic arithmetic

```sql
SELECT ("water_level" * 2) + 4 FROM "h2o_feet"
```

Output:

Name: h2o\_feet

| time | water_level |
| --- | --- |
| 2019-08-17T00:00:00Z | 20.2400000000 |
| 2019-08-17T00:00:00Z | 8.1280000000 |
| 2019-08-17T00:06:00Z | 20.0100000000 |
| 2019-08-17T00:06:00Z | 8.2320000000 |
| 2019-08-17T00:12:00Z | 19.7740000000 |
| 2019-08-17T00:12:00Z | 8.0560000000 |

The query multiplies `water_level`’s field values by two and adds four to those values.

**Note:** InfluxDB follows the standard order of operations. See [InfluxQL mathematical operators](/influxdb/cloud/query-data/influxql/math-operators/) for more on supported operators.

[](#select-all-data-from-more-than-one-measurement)

Select all data from more than one measurement

```sql
SELECT * FROM "h2o_feet","h2o_pH"
```

Output:

Name: h2o\_feet

| time | level description | location | pH | water_level |
| --- | --- | --- | --- | --- |
| 2019-08-17T00:00:00Z | below 3 feet | santa_monica |  | 2.0640000000 |
| 2019-08-17T00:00:00Z | between 6 and 9 feet | coyote_creek |  | 8.1200000000 |
| 2019-08-17T00:06:00Z | below 3 feet | santa_monica |  | 2.1160000000 |
| 2019-08-17T00:06:00Z | between 6 and 9 feet | coyote_creek |  | 8.0050000000 |
| 2019-08-17T00:12:00Z | below 3 feet | santa_monica |  | 2.0280000000 |
| 2019-08-17T00:12:00Z | between 6 and 9 feet | coyote_creek |  | 7.8870000000 |
| 2019-08-17T00:18:00Z | below 3 feet | santa_monica |  | 2.1260000000 |
| 2019-08-17T00:18:00Z | between 6 and 9 feet | coyote_creek |  | 7.7620000000 |

Name: h2o\_pH

| time | level description | location | pH | water_level |
| --- | --- | --- | --- | --- |
| 2019-08-17T00:00:00Z |  | coyote_creek | 7.00 |  |
| 2019-08-17T00:06:00Z |  | coyote_creek | 8.00 |  |
| 2019-08-17T00:06:00Z |  | santa_monica | 6.00 |  |
| 2019-08-17T00:12:00Z |  | coyote_creek | 8.00 |  |

The query selects all fields and tags from two measurements: `h2o_feet` and `h2o_pH`. Separate multiple measurements with a comma (`,`).

[](#select-all-data-from-a-measurement-in-a-particular-database)

Select all data from a measurement in a particular database

```sql
SELECT * FROM noaa.."h2o_feet"
```

Output:

Name: h2o\_feet

| time | level description | location | water_level |
| --- | --- | --- | --- |
| 2019-08-17T00:00:00Z | below 3 feet | santa_monica | 2.0640000000 |
| 2019-08-17T00:00:00Z | between 6 and 9 feet | coyote_creek | 8.1200000000 |
| 2019-08-17T00:06:00Z | below 3 feet | santa_monica | 2.1160000000 |
| 2019- 08-17T00:06:00Z | between 6 and 9 feet | coyote_creek | 8.0050000000 |
| 2019-08-17T00:12:00Z | below 3 feet | santa_monica | 2.0280000000 |
| 2019-08-17T00:12:00Z | between 6 and 9 feet | coyote_creek | 7.8870000000 |

The query selects data from the `h2o_feet` measurement in the `noaa` database. The `..` indicates the `DEFAULT` retention policy for the specified database.

## Common issues with the SELECT statement

### Selecting tag keys in the SELECT statement

A query requires at least one [field key](/influxdb/cloud/reference/glossary/#field-key) in the `SELECT` clause to return data. If the `SELECT` clause only includes a single [tag key](/influxdb/cloud/reference/glossary/#tag-key) or several tag keys, the query returns an empty response.

#### Example

The following query returns no data because it specifies a single tag key (`location`) in the `SELECT` clause:

```sql
SELECT "location" FROM "h2o_feet"
> No results
```

To return any data associated with the `location` tag key, the query’s `SELECT` clause must include at least one field key (`water_level`):

```sql
SELECT "water_level","location" FROM "h2o_feet"
```

Output:

Name: h2o\_feet

| time | water_level | location |
| --- | --- | --- |
| 2019-08-17T00:00:00Z | 8.1200000000 | coyote_creek |
| 2019-08-17T00:00:00Z | 2.0640000000 | santa_monica |
| 2019-08-17T 00:06:00Z | 8.0050000000 | coyote_creek |
| 2019-08-17T00:06:00Z | 2.1160000000 | santa_monica |
| 2019-08-17T00:12:00Z | 7.8870000000 | coyote_creek |
| 2019-08-17T00:12:00Z | 2.0280000000 | santa_monica |
| 2019-08-17T00:18:00Z | 7.7620000000 | coyote_creek |
| 2019-08-17T00:18:00Z | 2.1260000000 | santa_monica |

## Regular expressions

InfluxQL supports using [regular expressions](/influxdb/cloud/query-data/influxql/explore-data/regular-expressions/) when specifying:

-   [field keys](/influxdb/cloud/reference/glossary/#field-key) and [tag keys](/influxdb/cloud/reference/glossary/#tag-key) in the [`SELECT` clause](/influxdb/cloud/query-data/influxql/explore-data/select/)
-   [measurements](/influxdb/cloud/reference/glossary/#measurement) in the [`FROM` clause](/influxdb/cloud/query-data/influxql/explore-data/select/#from-clause)
-   [tag values](/influxdb/cloud/reference/glossary/#tag-value) and string [field values](/influxdb/cloud/reference/glossary/#field-value) in the [`WHERE` clause](/influxdb/cloud/query-data/influxql/explore-data/where/).
-   [tag keys](/influxdb/cloud/reference/glossary/#tag-key) in the [`GROUP BY` clause](/influxdb/cloud/query-data/influxql/explore-data/group-by/)

## Syntax

```sql
SELECT /<regular_expression_field_key>/ FROM /<regular_expression_measurement>/ WHERE [<tag_key> <operator> /<regular_expression_tag_value>/ | <field_key> <operator> /<regular_expression_field_value>/] GROUP BY /<regular_expression_tag_key>/
```

See [regular expressions](/influxdb/cloud/query-data/influxql/explore-data/regular-expressions/) for more information.

## Data types and cast operations

The [`SELECT` clause](#select-clause) supports specifying a [field’s](/influxdb/cloud/reference/glossary/#field) type and basic cast operations with the `::` syntax.

-   [Data types](#data-types)
-   [Cast operations](#cast-operations)

### Data types

[Field values](/influxdb/cloud/reference/glossary/#field-value) can be floats, integers, strings, or booleans. The `::` syntax allows users to specify the field’s type in a query.

**Note:** Generally, it is not necessary to specify the field value type in the [`SELECT` clause](/influxdb/cloud/query-data/influxql/explore-data/select/). In most cases, InfluxDB rejects any writes that attempt to write a [field value](/influxdb/cloud/reference/glossary/#field-value) to a field that previously accepted field values of a different type.

It is possible for field value types to differ across [shard groups](/influxdb/cloud/reference/glossary/#shard-group). In these cases, it may be necessary to specify the field value type in the `SELECT` clause. Please see the [Frequently Asked Questions](/influxdb/cloud/reference/faq/#how-does-influxdb-handle-field-type-discrepancies-across-shards) document for more information on how InfluxDB handles field value type discrepancies.

### Syntax

```sql
SELECT_clause <field_key>::<type> FROM_clause
```

`type` can be `float`, `integer`, `string`, or `boolean`. In most cases, InfluxDB returns no data if the `field_key` does not store data of the specified `type`. See [Cast Operations](#cast-operations) for more information.

### Example

```sql
SELECT "water_level"::float FROM "h2o_feet" LIMIT 4
```

Output:

Name: h2o\_feet

| time | water_level |
| --- | --- |
| 2019-08-17T00:00:00Z | 8.1200000000 |
| 2019-08-17T00:00:00Z | 2.0640000000 |
| 2019-08-17T00:06:00Z | 8.0050000000 |
| 2019-08-17T00:06:00Z | 2.1160000000 |

The query returns values of the `water_level` field key that are floats.

## Cast operations

The `::` syntax allows users to perform basic cast operations in queries. Currently, InfluxDB supports casting [field values](/influxdb/cloud/reference/glossary/#field-value) from integers to floats or from floats to integers.

### Syntax

```sql
SELECT_clause <field_key>::<type> FROM_clause
```

`type` can be `float` or `integer`.

InfluxDB returns no data if the query attempts to cast an integer or float to a string or boolean.

### Examples

[](#cast-float-field-values-to-integers)

Cast float field values to integers

```sql
SELECT "water_level"::integer FROM "h2o_feet" LIMIT 4
```

Output:

Name: h2o\_feet

| time | water_level |
| --- | --- |
| 2019-08-17T00:00:00Z | 8.0000000000 |
| 2019-08-17T00:00:00Z | 2.0000000000 |
| 2019-08-17T00:06:00Z | 8.0000000000 |
| 2019-08-17T00:06:00Z | 2.0000000000 |

The query returns the integer form of `water_level`’s float [field values](/influxdb/cloud/reference/glossary/#field-value).

[](#cast-float-field-values-to-strings-this-functionality-is-not-supported)

Cast float field values to strings (this functionality is not supported)

```sql
SELECT "water_level"::string FROM "h2o_feet" LIMIT 4
> No results
```

The query returns no data as casting a float field value to a string is not yet supported.

## Merge behavior

InfluxQL merges [series](/influxdb/cloud/reference/glossary/#series) automatically.

### Example

[](#merge-behavior)

Merge behavior

The `h2o_feet` [measurement](/influxdb/cloud/reference/glossary/#measurement) in the `noaa` is part of two [series](/influxdb/cloud/reference/glossary/#series). The first series is made up of the `h2o_feet` measurement and the `location = coyote_creek` [tag](/influxdb/cloud/reference/glossary/#tag). The second series is made of up the `h2o_feet` measurement and the `location = santa_monica` tag.

The following query automatically merges those two series when it calculates the average `water_level` using the [MEAN() function](/influxdb/cloud/query-data/influxql/functions/aggregates/#mean):

```sql
SELECT MEAN("water_level") FROM "h2o_feet"
```

Output:

Name: h2o\_feet

| time | mean |
| --- | --- |
| 1970-01-01T00:00:00Z | 4.4419314021 |

If you want the average `water_level` for the first series only, specify the relevant tag in the [`WHERE` clause](/influxdb/cloud/query-data/influxql/explore-data/where/):

```sql
SELECT MEAN("water_level") FROM "h2o_feet" WHERE "location" = 'coyote_creek'
```

Output:

Name: h2o\_feet

| time | mean |
| --- | --- |
| 1970-01-01T00:00:00Z | 5.3591424203 |

If you want the average `water_level` for each individual series, include a [`GROUP BY` clause](/influxdb/cloud/query-data/influxql/explore-data/group-by/):

```sql
SELECT MEAN("water_level") FROM "h2o_feet" GROUP BY "location"
```

Output:

name: h2o\_feet  
tags: location=coyote\_creek

| time | mean |
| --- | --- |
| 1970-01-01T00:00:00Z | 5.3591424203 |

name: h2o\_feet  
tags: location=santa\_monica

| time | mean |
| --- | --- |
| 1970-01-01T00:00:00Z | 3.5307120942 |

## Multiple statements

Separate multiple `SELECT` statements in a query with a semicolon (`;`).

### Examples

<!-- Tabbed content: Select one of the following options -->

**InfluxQL shell:**

In the [InfluxQL shell](/influxdb/cloud/tools/influxql-shell/):

```sql
SELECT MEAN("water_level") FROM "h2o_feet"; SELECT "water_level" FROM "h2o_feet" LIMIT 2
```

Output:

Name: h2o\_feet

| time | mean |
| --- | --- |
| 1970-01-01T00:00:00Z | 4.4419314021 |

Name: h2o\_feet

| time | water_level |
| --- | --- |
| 2019-08-17T00:00:00Z | 8.12 |
| 2015-08-18T00:00:00Z | 2.064 |

**InfluxDB API:**

With the [InfluxDB API](/influxdb/cloud/reference/api/influxdb-1x/):

```json
{
    "results": [
        {
            "statement_id": 0,
            "series": [
                {
                    "name": "h2o_feet",
                    "columns": [
                        "time",
                        "mean"
                    ],
                    "values": [
                        [
                            "1970-01-01T00:00:00Z",
                            4.442107025822522
                        ]
                    ]
                }
            ]
        },
        {
            "statement_id": 1,
            "series": [
                {
                    "name": "h2o_feet",
                    "columns": [
                        "time",
                        "water_level"
                    ],
                    "values": [
                        [
                            "2015-08-18T00:00:00Z",
                            8.12
                        ],
                        [
                            "2015-08-18T00:00:00Z",
                            2.064
                        ]
                    ]
                }
            ]
        }
    ]
}
```

<!-- End tabbed content -->