The formatting of the variable interpolation depends on the data source, but there are some situations where you might want to change the default formatting.
For example, the default for the MySql data source is to join multiple values as comma-separated with quotes: `'server01','server02'`. In some cases, you might want to have a comma-separated string without quotes: `server01,server02`. You can make that happen with advanced variable formatting options listed below.
## General syntax
Syntax: `${var_name:option}`
Test the formatting options on the [Grafana Play site](https://play.grafana.org/d/cJtIfcWiz/template-variable-formatting-options?orgId=1).
If any invalid formatting option is specified, then `glob` is the default/fallback option.
An alternative syntax (that might be deprecated in the future) is `[[var_name:option]]`.
## CSV
Formats multi-value variable as a comma-separated string.
```bash
servers = ['test1', 'test2']
String to interpolate: '${servers:csv}'
Interpolation result: 'test1,test2'
```
## Distributed - OpenTSDB
Formats multi-value variable in custom format for OpenTSDB.
```bash
servers = ['test1', 'test2']
String to interpolate: '${servers:distributed}'
Interpolation result: 'test1,servers=test2'
```
## Doublequote
Formats single- and multi-valued variables into a comma-separated string, escapes `"` in each value by `\"` and quotes each value with `"`.
```bash
servers = ['test1', 'test2']
String to interpolate: '${servers:doublequote}'
Interpolation result: '"test1","test2"'
```
## Glob - Graphite
Formats multi-value variable into a glob (for Graphite queries).
```bash
servers = ['test1', 'test2']
String to interpolate: '${servers:glob}'
Interpolation result: '{test1,test2}'
```
## JSON
Formats multi-value variable as a comma-separated string.
```bash
servers = ['test1', 'test2']
String to interpolate: '${servers:json}'
Interpolation result: '["test1", "test2"]'
```
## Lucene - Elasticsearch
Formats multi-value variable in Lucene format for Elasticsearch.
```bash
servers = ['test1', 'test2']
String to interpolate: '${servers:lucene}'
Interpolation result: '("test1" OR "test2")'
```
## Percentencode
Formats single and multi valued variables for use in URL parameters.