mirror of https://github.com/grafana/grafana.git
131 lines
4.9 KiB
Markdown
131 lines
4.9 KiB
Markdown
---
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aliases:
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- ../../data-sources/mssql/template-variables/
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description: Using template variables with Microsoft SQL Server in Grafana
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keywords:
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- grafana
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- MSSQL
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- Microsoft
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- SQL
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- Azure SQL Database
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- templates
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- variables
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- queries
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labels:
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products:
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- cloud
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- enterprise
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- oss
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menuTitle: Template variables
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title: Microsoft SQL Server template variables
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weight: 400
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refs:
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variables:
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- pattern: /docs/grafana/
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destination: /docs/grafana/<GRAFANA_VERSION>/dashboards/variables/
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- pattern: /docs/grafana-cloud/
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destination: /docs/grafana/<GRAFANA_VERSION>/dashboards/variables/
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variable-syntax-advanced-variable-format-options:
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- pattern: /docs/grafana/
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destination: /docs/grafana/<GRAFANA_VERSION>/dashboards/variables/variable-syntax/#advanced-variable-format-options
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- pattern: /docs/grafana-cloud/
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destination: /docs/grafana/<GRAFANA_VERSION>/dashboards/variables/variable-syntax/#advanced-variable-format-options
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add-template-variables:
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- pattern: /docs/grafana/
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destination: /docs/grafana/<GRAFANA_VERSION>/dashboards/variables/add-template-variables/
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- pattern: /docs/grafana-cloud/
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destination: /docs/grafana/<GRAFANA_VERSION>/dashboards/variables/add-template-variables/
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---
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# Microsoft SQL Server template variables
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Instead of hard-coding details such as server, application, and sensor names in metric queries, you can use variables.
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Grafana displays these variables in drop-down select boxes at the top of the dashboard to help you change the data displayed in your dashboard.
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Grafana refers to such variables as **template variables**.
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For general information on using variables in Grafana, refer to [Add variables](ref:add-template-variables).
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For an introduction to templating and template variables, refer to [Templating](ref:variables) and [Add and manage variables](ref:add-template-variables).
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## Query variable
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A query variable in Grafana dynamically retrieves values from your data source using a query. With a query variable, you can write a SQL query that returns values such as measurement names, key names, or key values that are shown in a drop-down select box.
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For example, the following query returns all values from the `hostname` column:
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```sql
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SELECT hostname FROM host
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```
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A query can return multiple columns, and Grafana automatically generates a list using the values from those columns. For example, the following query returns values from both the `hostname` and `hostname2` columns, which are included in the variable's drop-down list.
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```sql
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SELECT [host].[hostname], [other_host].[hostname2] FROM host JOIN other_host ON [host].[city] = [other_host].[city]
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```
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You can also create a key/value variable using a query that returns two columns named `__text` and `__value`.
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- The `__text` column defines the label shown in the drop-down.
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- The `__value` column defines the value passed to panel queries.
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This is useful when you want to display a user-friendly label (like a hostname) but use a different underlying value (like an ID).
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Note that the values in the `_text` column should be unique. If there are duplicates, Grafana uses only the first matching entry.
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```sql
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SELECT hostname __text, id __value FROM host
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```
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You can also create nested variables, where one variable depends on the value of another. For example, if you have a variable named `region`, you can configure a `hosts` variable to only show hosts from the selected region. If `region` is a multi-value variable, use the `IN` operator instead of `=` to match against multiple selected values.
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```sql
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SELECT hostname FROM host WHERE region IN ($region)
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```
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## Use variables in queries
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Grafana automatically quotes template variable values only when the template variable is a `multi-value`.
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When using a multi-value variable, use the `IN` comparison operator instead of `=` to match against multiple values.
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Grafana supports two syntaxes for using variables in queries:
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- **`$<varname>` syntax**
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Example with a template variable named `hostname`:
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```sql
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SELECT
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atimestamp time,
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aint value
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FROM table
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WHERE $__timeFilter(atimestamp) and hostname in($hostname)
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ORDER BY atimestamp
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```
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- **`[[varname]]` syntax**
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Example with a template variable named `hostname`:
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```sql
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SELECT
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atimestamp as time,
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aint as value
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FROM table
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WHERE $__timeFilter(atimestamp) and hostname in([[hostname]])
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ORDER BY atimestamp
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```
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### Disable quoting for multi-value variables
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By default, Grafana formats multi-value variables as a quoted, comma-separated string. For example, if `server01` and `server02` are selected, the result will be `'server01'`, `'server02'`. To disable quoting, use the `csv` formatting option for variables:
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```text
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${servers:csv}
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```
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This outputs the values as an unquoted comma-separated list.
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Refer to [Advanced variable format options](ref:variable-syntax-advanced-variable-format-options) for additional information.
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