old_contents: import frappe
  
  def execute():
  	frappe.db.sql("""
  		UPDATE `tabLeave Type`
  		SET max_days_allowed = '0'
  		WHERE trim(coalesce(max_days_allowed, '')) = ''
  	""")
  	frappe.db.sql_ddl("""ALTER table `tabLeave Type` modify max_days_allowed int(8) NOT NULL""")
  
  
new_contents: import frappe
  
  def execute():
  	frappe.db.sql("""
  		UPDATE `tabLeave Type`
  		SET max_days_allowed = '0'
  		WHERE trim(coalesce(max_days_allowed, '')) = ''
  	""")
  	frappe.db.sql_ddl("""ALTER table `tabLeave Type` modify max_days_allowed int(8) NOT NULL""")
  	frappe.reload_doc("hr", "doctype", "leave_type")
  	rename_field("Leave Type", "max_days_allowed", "max_continuous_days_allowed")
  
  
subject: Add rename_field