# rename()

`rename(col as alias [, ...col as alias]`) renames one or more columns in the input stream.

`alias` can be one word or include spaces. Aliases with spaces must be enclosed in quotation marks. If `alias` is the name of an existing column, `rename` will overwrite its values with the values of `col`.

Columns are renamed in order:

* `rename col1 as foo, col2 as foo` will first rename `col1` as `foo`, then rename `col2` as `foo` . `foo` will contain the values of `col2` ; the values of `col1` will not exist in the output.
* `rename col1 as foo, foo as bar` will rename `col1` as `foo`, then rename `foo` as `bar`. `bar` will be contain the values of `col1`; `foo` will not exist.

`rename` has no effect if `col` and `alias` do not exist. If `col` does not exist and `alias` is the name of an existing column, `alias` will not exist.

A column cannot have multiple aliases, e.g. `rename col1 as foo, col1 as bar` is not valid.

## Returns

The same table as the input with specified columns renamed to aliases. If a column was renamed, the original column name does not exist in the output.

## Examples

```python
# Rename a column
* | rename elapsed_ms as Latency

# Rename a column to a name with spaces
* | rename elapsed_ms as "Latency in milliseconds"

# Rename multiple columns
* | rename elapsed_ms as Latency, hostname as Host
```