> For the complete documentation index, see [llms.txt](https://cortex-docs.paloaltonetworks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cortex-docs.paloaltonetworks.com/xql-command-reference-guide/readme/functions/subtract.md).

# subtract

Use the `subtract()` function to calculate the difference between two numbers by subtracting the second argument from the first.

## Syntax

```sql
subtract (<value_1>, <value_2>)
```

## Parameters

| Name      | Type                   | Required | Description                                                   |
| --------- | ---------------------- | -------- | ------------------------------------------------------------- |
| `value_1` | integer, float, string | Yes      | The first value (the minuend).                                |
| `value_2` | integer, float, string | Yes      | The second value (the subtrahend) to subtract from the first. |

## Returns

The `subtract()` function returns the numerical difference between the two input numbers.

## Usage notes

* The function accepts numeric literals, floating-point numbers, and integers.
* The function supports integers or numbers provided as a string type (for example, extracted from a data field).

## Examples

### Example 1: Subtracting an integer literal from an integer field

**Goal**: Subtract a specific integer literal from an existing integer field to create a new field.

**XQL code**:

```sql
config timeframe = 1d
| dataset = sample_xql_raw
| alter reduced_event_id = subtract(event_id, 5)
| fields event_id, reduced_event_id
| limit 3
```

**Explanation**: This query calculates `reduced_event_id` by subtracting 5 from each `event_id`. For `event_id` 101, the result is 96.

**Output**:

| EVENT\_ID | REDUCED\_EVENT\_ID |
| --------- | ------------------ |
| 101       | 96                 |
| 102       | 97                 |
| 103       | 98                 |

### Example 2: Subtracting a floating-point literal from a floating-point field

**Goal**: Subtract a floating-point literal from an existing floating-point field.

**XQL code**:

```sql
config timeframe = 1d
| dataset = sample_xql_raw
| alter adjusted_duration = subtract(duration_seconds, 0.75)
| fields event_id, duration_seconds, adjusted_duration
| limit 3
```

**Explanation**: Here, `duration_seconds` (which contains decimal values like 1.5 and 0.8) is decreased by 0.75, producing new floating-point values in `adjusted_duration`.

**Output**:

| EVENT\_ID | DURATION\_SECONDS | ADJUSTED\_DURATION |
| --------- | ----------------- | ------------------ |
| 101       | 1.5               | 0.75               |
| 102       | 0.8               | 0.05               |
| 103       | 10.2              | 9.45               |

### Example 3: Subtracting one field from another field

**Goal**: Calculate the difference between values in two different fields.

**XQL code**:

```sql
config timeframe = 1d
| dataset = sample_xql_raw
| alter difference_in_ids = subtract(event_id, arrayindex(numeric_codes, 0))
| fields event_id, numeric_codes, difference_in_ids
| limit 3
```

**Explanation**: For `event_id` 101, `event_id` is 101 and the first element of `numeric_codes` (index 0) is 13, resulting in 101 - 13 = 88. For `event_id` 102, `event_id` is 102 and the first `numeric_code` is -21, so 102 - (-21) = 123.

**Output**:

| EVENT\_ID | NUMERIC\_CODES     | DIFFERENCE\_IN\_IDS |
| --------- | ------------------ | ------------------- |
| 101       | \[13, -47, 29,...] | 88                  |
| 102       | \[-21, 56, 13,...] | 123                 |
| 103       | \[90, -33, 7,...]  | 13                  |

### Example 4: Handling negative numbers (subtracting a negative literal)

**Goal**: Demonstrate the behavior when subtracting a negative number.

**XQL code**:

```sql
config timeframe = 1d
| dataset = sample_xql_raw
| alter negative_subtraction = subtract(duration_seconds, -2.0)
| fields event_id, duration_seconds, negative_subtraction
| limit 3
```

**Explanation**: For `event_id` 101, `duration_seconds` is 1.5. Subtracting -2.0 (which is equivalent to adding 2.0) results in 3.5. This aligns with the understanding that the `subtract()` function supports operations with negative numbers.

**Output**:

| EVENT\_ID | DURATION\_SECONDS | NEGATIVE\_SUBTRACTION |
| --------- | ----------------- | --------------------- |
| 101       | 1.5               | 3.5                   |
| 102       | 0.8               | 2.8                   |
| 103       | 10.2              | 12.2                  |

### Example 5: Subtracting a numeric value extracted from JSON data

**Goal**: Extract a number from a JSON field and perform a subtraction operation on it.

**XQL code**:

```sql
config timeframe = 1d
| dataset = sample_xql_raw
| filter simple_json_data != null
| alter json_code_number = to_number(simple_json_data -> "code")
| alter reduced_json_value = subtract(json_code_number, 50)
| fields event_id, simple_json_data, json_code_number, reduced_json_value
| limit 3
```

**Explanation**: This query extracts the `code` value (for example, "200") from the `simple_json_data` field as a string, converts it to a number using `to_number()`, and then subtracts 50 from it. Note that only `event_id` 101 has a "code" field in `simple_json_data` in the `sample_xql_raw` dataset.

**Output**:

| EVENT\_ID | SIMPLE\_JSON\_DATA            | JSON\_CODE\_NUMBER | REDUCED\_JSON\_VALUE |
| --------- | ----------------------------- | ------------------ | -------------------- |
| 101       | {"status": "ok", "code": 200} | 200                | 150                  |

## Related articles

* **Stages**: [`alter`](/xql-command-reference-guide/readme/stages/alter.md)
* **Functions**: [`arrayindex`](/xql-command-reference-guide/readme/functions/arrayindex.md), [`to_number`](/xql-command-reference-guide/readme/functions/to_number.md)


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://cortex-docs.paloaltonetworks.com/xql-command-reference-guide/readme/functions/subtract.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.