Column aliases

ServiceNow maintains a table of field-column name mappings: sys_storage_alias. It is especially useful when reviewing list of indexes available in a table like cmdb_ci_storage_device. Index definition may include a storage alias instead of human-readable name of the field.

For example, cmdb_ci_storage_device.computer field has a storage alias a_ref_3.

Reason for alias use is probably related to the way table structure is organized. Alias (most probably) won't be used if table is stand-alone. If table is part of hierarchy and table-per-hierarchy or table-per-partition extension models are used, then column with the same names will to be mapped to aliases. E.g. cmdb_os_user.computer and cmdb_ci_storage_device.computer have computer and a_ref_3 aliases.

What do we know about variables?

Tables

Let's take a look from request perspective:

• sc_req_item is a request item table
• sc_item_option_mtom is a m2m table to keep links between a request item and a variable value
• sc_item_option is a table of variable values (options)

Now let's take a cart perspective:

• sc_cart is a table where all cart records are present
• sc_cart_item is a table of request items in a cart
• sc_item_option is a table of variables and their values (options) of the items in a cart

APIs

It's mentioned somewhere in OOTB code. If I reference a variable Order From in a business rule of a request item, I'll get a reference to an instance of something sort of GlideElement. Suppose it's a v - reference to a variable. Then the following chain of methods is available.

var question = v.getGlideObject().getQuestion();

question.getLabel();
// "Order From"

You can list available attributes in the js object question for more methods. In fact all variable properties are accessible from it.