Update sl-jdbc.md

updating for dimension only queries

website/docs/docs/dbt-cloud-apis/sl-jdbc.md

@@ -165,17 +165,17 @@ select * from {{
 
 ## Querying the API for metric values
 
-To query metric values, here are the following parameters that are available:
+To query metric values, here are the following parameters that are available. Your query must have _either_ a `metric` **or** a `group_by` parameter to be valid. 
 
-| Parameter | Description  | Example    | Type |
-| --------- | -----------| ------------ | -------------------- |
-| `metrics`   | The metric name as defined in your dbt metric configuration   | `metrics=['revenue']` | Required    |
-| `group_by`  | Dimension names or entities to group by. We require a reference to the entity of the dimension (other than for the primary time dimension), which is pre-appended to the front of the dimension name with a double underscore. | `group_by=['user__country', 'metric_time']`     | Optional   |
-| `grain`   | A parameter specific to any time dimension and changes the grain of the data from the default for the metric. | `group_by=[Dimension('metric_time')` <br/> `grain('week\|day\|month\|quarter\|year')]` | Optional     |
-| `where`     | A where clause that allows you to filter on dimensions and entities using parameters. This takes a filter list OR string. Inputs come with `Dimension`, and `Entity` objects. Granularity is required if the `Dimension` is a time dimension | `"{{ where=Dimension('customer__country') }} = 'US')"`   | Optional   |
-| `limit`   | Limit the data returned    | `limit=10` | Optional  |
-|`order`  | Order the data returned by a particular field     | `order_by=['order_gross_profit']`, use `-` for descending, or full object notation if the object is operated on: `order_by=[Metric('order_gross_profit').descending(True)`]   | Optional   |
-| `compile`   | If true, returns generated SQL for the data platform but does not execute | `compile=True`   | Optional |
+| Parameter | Description  | Example    | 
+| --------- | -----------| ------------ |
+| `metrics`   | The metric name as defined in your dbt metric configuration   | `metrics=['revenue']` | 
+| `group_by`  | Dimension names or entities to group by. We require a reference to the entity of the dimension (other than for the primary time dimension), which is pre-appended to the front of the dimension name with a double underscore. | `group_by=['user__country', 'metric_time']`    |
+| `grain`   | A parameter specific to any time dimension and changes the grain of the data from the default for the metric. | `group_by=[Dimension('metric_time')` <br/> `grain('week\|day\|month\|quarter\|year')]` | 
+| `where`     | A where clause that allows you to filter on dimensions and entities using parameters. This takes a filter list OR string. Inputs come with `Dimension`, and `Entity` objects. Granularity is required if the `Dimension` is a time dimension | `"{{ where=Dimension('customer__country') }} = 'US')"`   | 
+| `limit`   | Limit the data returned    | `limit=10` | 
+|`order`  | Order the data returned by a particular field     | `order_by=['order_gross_profit']`, use `-` for descending, or full object notation if the object is operated on: `order_by=[Metric('order_gross_profit').descending(True)`]   | 
+| `compile`   | If true, returns generated SQL for the data platform but does not execute | `compile=True`  | 
 
 
 
@@ -248,6 +248,16 @@ select * from {{
 	}}
 ``` 
 
+### Query only a dimension
+
+In this case, you'll get the full list of dimension values for the chosen dimension.
+
+```bash
+select * from {{
+    semantic_layer.query(group_by=['customer__customer_type'])
+                  }}
+```
+
 ### Query with where filters
 
 Where filters in API allow for a filter list or string. We recommend using the filter list for production applications as this format will realize all benefits from the <Term id="predicate-pushdown"  /> where possible.