## CONCAT

The `CONCAT` function in ES|QL is used to concatenate two or more strings together.

### Examples

Here are a couple of examples of how you can use the `CONCAT` function in ES|QL:

```esql
FROM employees
| KEEP first_name, last_name
| EVAL fullname = CONCAT(first_name, " ", last_name)
```

In this example, the `CONCAT` function is used to combine the `first_name` and `last_name` fields from the `employees` index, with a space in between, to create a new field called `fullname`.

```esql
FROM logs-*
| EVAL message = CONCAT("Error occurred at ", @timestamp, ": ", error_message)
```

In this second example, the `CONCAT` function is used to create a descriptive error message by combining a static string, the `@timestamp` field, and the `error_message` field from the `logs-*` index.