1. A method comprising: receiving, from a user, a selection of an existing report field from a plurality of report fields displayed in an existing report table, each of the report fields in the existing report table storing a plurality of source values, the plurality of source values for each of the report fields being associated with a record of a plurality of records in the existing report table; prompting the user to input a name that will be used to identify a new user-created report field, wherein the new user-created report field will store a plurality of user-created target categories in the existing report table; determining a data type of the plurality of source values stored in the selected report field; providing a data type-specific mapping interface that is displayed to the user, the provided data type-specific mapping interface being specific to the determined data type of the plurality of source values; receiving, from the user via the data type-specific mapping interface, a selection identifying a subset of the source values for mapping to a user-created target category of the plurality of user-created target categories stored in the new user-created report field; prompting, via the data type-specific mapping interface, the user to input a name used to identify the user-created target category; mapping each source value of the subset of source values to the user-created target category using the data type-specific mapping interface; and updating the existing report table to include the new user-created report field, where each record of the plurality of records associated with the subset of the source values is also associated with the user-created target category.