input: Write a python function to create a histogram from a SQL query result using pandas and matplotlib.
  assert isinstance(create_histogram("SELECT column_name FROM table_name", db), plt.Figure)
  assert create_histogram("SELECT column_name FROM table_name WHERE column_name > 10", db).axes[0].get_title() == ''
  assert create_histogram("SELECT column_name FROM table_name", db).axes[0].get_xlabel() == 'column_name'
output: def create_histogram(query, db):
      import pandas as pd
      import matplotlib.pyplot as plt
  
      # Execute the SQL query and load the result into a DataFrame
      df = pd.read_sql(query, db)
  
      # Extract the column name from the query
      column_name = query.split()[1]
  
      # Create the histogram
      fig, ax = plt.subplots()
      df[column_name].plot(kind='hist', ax=ax)
  
      # Set the x-axis label
      ax.set_xlabel(column_name)
  
      return fig