Good Read – https://dataopsschool.com/blog/databricks-catalog-schemas-tables-with-external-location/

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1. Create Catalog without External Location

• Go to Catalog tab in Databricks workspace.
• Click “+ Add Catalog”.
• Provide a catalog name (e.g., Dev).
• Choose type = Standard.
• Do not specify any external location → data defaults to metastore location.
• Click Create → Catalog is created with default schemas (default, information_schema).
• To check catalog details: DESCRIBE CATALOG EXTENDED Dev; (Shows no location specified → fallback to metastore storage.)

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2. Create Catalog with SQL

• Open a SQL notebook in Databricks.
• Ensure cluster is Unity Catalog enabled.
• Run SQL command: CREATE CATALOG DevSQL COMMENT "This catalog is created using SQL";
• Verify with: DESCRIBE CATALOG EXTENDED DevSQL;

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3. Drop Catalog and Drop Catalog Recursively

• To drop a catalog: DROP CATALOG DevSQL; ❌ Error → cannot drop because it contains schemas/tables.
• Use CASCADE to drop everything inside recursively: DROP CATALOG DevSQL CASCADE; ✅ Removes catalog + schemas + tables.

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4. Create External Location in Databricks

• Go to Catalog > External Data > Create Location.
• Or via SQL: CREATE EXTERNAL LOCATION `ext_catalogs` URL 'abfss://data@<storage_account>.dfs.core.windows.net/ADB/catalog/' WITH STORAGE CREDENTIAL `SC_catalog_storage`;

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5. Create Storage Credential in Databricks

• Navigate to Catalog > Storage Credentials > Create Credential.
• Choose Azure Managed Identity.
• Provide credential name (e.g., SC_catalog_storage).
• Supply UC connector Resource ID (from Azure portal).
• Click Create → Storage credential created.

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6. Create Catalog with External Location

• Run SQL to create a catalog with managed location:

CREATE CATALOG DevEXT
MANAGED LOCATION 'abfss://data@<storage_account>.dfs.core.windows.net/ADB/catalog/'
COMMENT "Catalog with external location";

• Verify:

DESCRIBE CATALOG EXTENDED DevEXT;

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Final Flow Summary

1. Create Catalog without external location → defaults to metastore.
2. Create Catalog using SQL.
3. Drop catalog normally or recursively with CASCADE.
4. Create External Location in Databricks.
5. Create Storage Credential for external storage.
6. Create Catalog with External Location bound to that credential.

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Let’s build a practical example using your catalog dev_ext.
I’ll show you:

1. Create a schema inside the catalog.
2. Create a table in that schema.
3. Insert sample data.
4. Query the data back.

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1️⃣ Create a Schema in dev_ext

-- Create a schema called bronze inside catalog dev_ext
CREATE SCHEMA IF NOT EXISTS dev_ext.bronze
COMMENT 'Bronze schema for raw ingested data in dev_ext catalog';

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2️⃣ Create a Managed Table in the Schema

-- Create a managed table (no LOCATION clause → stored at catalog/schema location)
CREATE TABLE IF NOT EXISTS dev_ext.bronze.sales_data (
  id INT,
  product STRING,
  amount DOUBLE,
  sale_date DATE
)
COMMENT 'Sales transactions table';

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3️⃣ Insert Some Sample Data

INSERT INTO dev_ext.bronze.sales_data VALUES
  (1, 'Laptop', 1200.50, DATE'2025-08-01'),
  (2, 'Phone', 750.00, DATE'2025-08-05'),
  (3, 'Tablet', 500.00, DATE'2025-08-10'),
  (4, 'Headphones', 120.00, DATE'2025-08-12');

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4️⃣ Query the Data

SELECT * 
FROM dev_ext.bronze.sales_data;

✅ You’ll see the four rows returned.

• The data files will be stored in the catalog-level managed location (since you didn’t set schema/table LOCATION).

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