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* Update all links that have destinations outside of /docs/grafana/latest/datasources/ to use docs/reference shortcode Signed-off-by: Jack Baldry <jack.baldry@grafana.com> * Fix typo Signed-off-by: Jack Baldry <jack.baldry@grafana.com> * Prettier Signed-off-by: Jack Baldry <jack.baldry@grafana.com> --------- Signed-off-by: Jack Baldry <jack.baldry@grafana.com>
112 lines
4.6 KiB
Markdown
112 lines
4.6 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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---
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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 lists these variables in dropdown 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 an introduction to templating and template variables, refer to the [Templating][variables] and [Add and manage variables][add-template-variables] documentation.
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## Query variable
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If you add a template variable of the type `Query`, you can write a MS SQL query that can
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return things like measurement names, key names or key values that are shown as a dropdown select box.
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For example, you can have a variable that contains all values for the `hostname` column in a table if you specify a query like this in the templating variable **Query** setting.
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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 will automatically create a list from them. For example, the query below will return a list with values from `hostname` and `hostname2`.
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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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Another option is a query that can create a key/value variable. The query should return two columns that are named `__text` and `__value`. The `__text` column value should be unique (if it is not unique then the first value is used). The options in the dropdown will have a text and value that allow you to have a friendly name as text and an id as the value. An example query with `hostname` as the text and `id` as the value:
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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. For example, if you had another variable named `region`. Then you could have
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the hosts variable only show hosts from the current selected region with a query like this (if `region` is a multi-value variable, then use the `IN` comparison operator rather than `=` to match against multiple values):
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```sql
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SELECT hostname FROM host WHERE region IN ($region)
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```
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## Using variables in queries
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> From Grafana 4.3.0 to 4.6.0, template variables are always quoted automatically so if it is a string value do not wrap them in quotes in where clauses.
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>
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> From Grafana 5.0.0, template variable values are only quoted when the template variable is a `multi-value`.
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If the variable is a multi-value variable then use the `IN` comparison operator rather than `=` to match against multiple values.
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There are two syntaxes:
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`$<varname>` 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]]` 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 $__timeFilter(atimestamp) and hostname in([[hostname]])
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ORDER BY atimestamp
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```
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### Disabling Quoting for Multi-value Variables
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Grafana automatically creates a quoted, comma-separated string for multi-value variables. For example: if `server01` and `server02` are selected then it will be formatted as: `'server01', 'server02'`. To disable quoting, use the csv formatting option for variables:
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`${servers:csv}`
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Read more about variable formatting options in the [Variables][variable-syntax-advanced-variable-format-options] documentation.
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{{% docs/reference %}}
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[add-template-variables]: "/docs/grafana/ -> /docs/grafana/<GRAFANA VERSION>/dashboards/variables/add-template-variables"
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[add-template-variables]: "/docs/grafana-cloud/ -> /docs/grafana/<GRAFANA VERSION>/dashboards/variables/add-template-variables"
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[variable-syntax-advanced-variable-format-options]: "/docs/grafana/ -> /docs/grafana/<GRAFANA VERSION>/dashboards/variables/variable-syntax#advanced-variable-format-options"
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[variable-syntax-advanced-variable-format-options]: "/docs/grafana-cloud/ -> /docs/grafana/<GRAFANA VERSION>/dashboards/variables/variable-syntax#advanced-variable-format-options"
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[variables]: "/docs/grafana/ -> /docs/grafana/<GRAFANA VERSION>/dashboards/variables"
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[variables]: "/docs/grafana-cloud/ -> /docs/grafana/<GRAFANA VERSION>/dashboards/variables"
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{{% /docs/reference %}}
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