How can I create an external table in Unity Catalog using the Delta Lake format?
To create an external table in Unity Catalog using the Delta Lake format, you can follow these steps:

1. First, you need to create an external location in Unity Catalog. This can be done using the Databricks SQL endpoint or the Unity Catalog API. Here's an example of how to create an external location using the Databricks SQL endpoint:
```sql
CREATE EXTERNAL LOCATION my_external_location
USING 's3://my-bucket/my-path'
WITH DBPROPERTIES ('format' = 'delta')
```
In this example, `my_external_location` is the name of the external location, `s3://my-bucket/my-path` is the path to the S3 bucket where the data is stored, and `delta` is the format of the data.

2. Once you have created an external location, you can create an external table that references the data in that location. Here's an example of how to create an external table using the Databricks SQL endpoint:
```sql
CREATE EXTERNAL TABLE my_external_table
STORED AS DELTA
LOCATION 's3://my-bucket/my-path'
TBLPROPERTIES ('delta.autoOptimize.optimizeWrite' = 'true', 'delta.autoOptimize.autoCompact' = 'true')
```
In this example, `my_external_table` is the name of the external table, `DELTA` is the format of the data, `s3://my-bucket/my-path` is the path to the data, and `delta.autoOptimize.optimizeWrite` and `delta.autoOptimize.autoCompact` are table properties that enable automatic optimization of the Delta Lake table.

Note that these examples assume that you have already created an external location and have the necessary permissions to access the data in that location. You will also need to replace the placeholders with the actual values for your use case.