feat(add-data): Add script for SQL schema initialization

Since we are working with an Azure SQL database, we need to fill the
generated customer data in a fitting schema. The schema will be
described in more detail in an updated README file later.

The added script uses `pyodbc` to connect to the database and create the
tables. This requires a connection string, which will not be checked out
to this repo for security reasons and must be obtained separately.

Additionally, a script `test_sql_connection.py` is added with this
commit, which is a simple utility to test the `pyodbc` connection.

data_preparation/test_sql_connection.py

@@ -0,0 +1,56 @@
+"""Script to test connection to Azure SQL Database."""
+
+import os
+
+import pyodbc
+
+
+def test_connection() -> bool:
+    """Test the connection to Azure SQL Database.
+
+    This function attempts to establish a connection to an Azure SQL Database
+    using a connection string stored in the environment variable
+    'AZURE_SQL_CONNECTION_STRING'. It executes a simple query to verify
+    the connection and prints the result of the connection attempt.
+
+    Returns
+    -------
+    bool
+        True if the connection was successful and closed properly,
+        False if there was an error connecting to the database.
+
+    Notes
+    -----
+    - The function requires the 'AZURE_SQL_CONNECTION_STRING' environment
+      variable to be set with a valid connection string.
+    - It uses pyodbc to establish the database connection.
+    - The function prints success or error messages to stdout.
+    - In case of a successful connection, it executes "SELECT @@version;"
+      as a test query.
+    - The function ensures that both the cursor and the connection are
+      closed after the operation, regardless of its success or failure.
+    """
+    connection_string = os.environ.get("AZURE_SQL_CONNECTION_STRING")
+    try:
+        conn = pyodbc.connect(connection_string)
+        cursor = conn.cursor()
+        print("Connected to Azure SQL Database successfully!")
+
+        # Example query
+        cursor.execute("SELECT @@version;")
+
+    except pyodbc.Error as e:
+        print(f"Error connecting to Azure SQL Database: {e}")
+        return False
+
+    finally:
+        if "cursor" in locals():
+            cursor.close()
+        if "conn" in locals():
+            conn.close()
+
+    return True
+
+
+if __name__ == "__main__":
+    test_connection()