Update Streamlit Lakebase docs

Author: pbv0

docs/docs/streamlit/tables/lakebase_read.mdx

@@ -0,0 +1,118 @@
+---
+sidebar_position: 1
+---
+
+# Read a Lakebase table
+
+This app connects to a [Databricks Lakebase](https://docs.databricks.com/aws/en/oltp/) OLTP database instance and reads the first 100 rows from any table. Provide the instance name, database, schema, and table name.
+
+## Code snippet
+
+```python title="app.py"
+import os
+import pandas as pd
+import psycopg
+from databricks.sdk import WorkspaceClient
+import streamlit as st
+
+
+w = WorkspaceClient()
+
+
+def get_connection(host: str, database: str, user: str) -> psycopg.Connection:
+    """Get a connection to the Lakebase database using OAuth token."""
+    token = w.config.oauth_token().access_token
+    
+    return psycopg.connect(
+        host=host,
+        port=5432,
+        dbname=database,
+        user=user,
+        password=token,
+        sslmode="require",
+    )
+
+
+def query_df(host: str, database: str, user: str, sql: str) -> pd.DataFrame:
+    """Execute a SQL query and return results as a DataFrame."""
+    conn = get_connection(host, database, user)
+    try:
+        with conn.cursor() as cur:
+            cur.execute(sql)
+            if not cur.description:
+                return pd.DataFrame()
+            
+            cols = [d.name for d in cur.description]
+            rows = cur.fetchall()
+            return pd.DataFrame(rows, columns=cols)
+    finally:
+        conn.close()
+
+
+# Get connection parameters from environment variables (set by Databricks Apps)
+# or fall back to manual configuration
+host = os.getenv("PGHOST")
+database = os.getenv("PGDATABASE")
+user = os.getenv("PGUSER")
+
+if not all([host, database, user]):
+    # Manual configuration if environment variables are not set
+    instance_name = "your_instance_name"
+    database = "databricks_postgres"
+    user = w.config.client_id or w.current_user.me().user_name
+    host = w.database.get_database_instance(name=instance_name).read_write_dns
+
+# Query table
+schema = "public"
+table = "your_table_name"
+df = query_df(host, database, user, f"SELECT * FROM {schema}.{table} LIMIT 100")
+st.dataframe(df)
+```
+
+:::tip
+
+Add your Lakebase instance as an App resource to automatically configure connection parameters via environment variables. See the [Lakebase resource documentation](https://docs.databricks.com/aws/en/dev-tools/databricks-apps/lakebase) for details.
+
+:::
+
+:::warning
+
+Tokens expire periodically; this app refreshes on each new connection and enforces TLS (sslmode=require).
+
+:::
+
+## Resources
+
+- [Lakebase](https://docs.databricks.com/aws/en/oltp/) database instance (Postgres).
+- An existing Postgres database, schema, and table with data.
+
+## Permissions
+
+Add the Lakebase instance as an [**App resource**](https://docs.databricks.com/aws/en/dev-tools/databricks-apps/lakebase) to automatically configure permissions and environment variables (`PGHOST`, `PGDATABASE`, `PGUSER`, etc.).
+
+Alternatively, manually create a Postgres role for the service principal. See [this guide](https://docs.databricks.com/aws/en/oltp/pg-roles?language=PostgreSQL#create-postgres-roles-and-grant-privileges-for-databricks-identities).
+
+Example grants for read access:
+
+```sql
+GRANT CONNECT ON DATABASE databricks_postgres TO "<service-principal-id>";
+GRANT USAGE ON SCHEMA public TO "<service-principal-id>";
+GRANT SELECT ON TABLE your_table_name TO "<service-principal-id>";
+```
+
+[This guide](https://docs.databricks.com/aws/en/oltp/query/sql-editor#create-a-new-query) shows you how to query your Lakebase.
+
+## Dependencies
+
+- [Databricks SDK](https://pypi.org/project/databricks-sdk/) - `databricks-sdk>=0.60.0`
+- [Psycopg](https://pypi.org/project/psycopg/) - `psycopg[binary]`
+- [Pandas](https://pypi.org/project/pandas/) - `pandas`
+- [Streamlit](https://pypi.org/project/streamlit/) - `streamlit`
+
+```python title="requirements.txt"
+databricks-sdk>=0.60.0
+pandas
+streamlit
+psycopg[binary]
+```
+