1. Appendix A: Data Types

Last Updated 10/30/2023

What is a Data Type?

A Data type is the format that determines how a field is stored within Evergreen. For example, dates are stored in a timestamp format and the title of an item is stored as text. Both timestamp and text are specific data types which tell Evergreen what can be done with the field.

The central column of the Database Source Browser lists Field Name and Data Type for the selected database table.

Each data type has its own characteristics and uses:

Data Type	Description	Notes
id	Unique number assigned by the database to identify a record	A number that is a meaningful reference for the database but not of much use to a human user. Use in displayed fields when counting records or in filters.
int	Integer	The field contains numbers only.
interval	The field contains time intervals, such as "2 weeks" or "6 months"	The recurrence interval for fines and the time limit for age hold protection are stored as intervals.
money	Number in dollars	Fields with the money data type contain monetary amounts, such as the amount billed to a patron on a billing line item.
text	Text field	Usually uses the Raw Data transform.
timestamp	Exact date and time	Select appropriate date/time transform. Raw Data includes second and time zone information, usually more than is required for a report.
bool	True or False	Commonly used to filter out deleted item or patron records.
org_unit	A number representing a library, library system, or federation	Abbreviation of "organizational unit". When you want to filter on a library, make sure that the field name is on an org_unit or id data type.
link	A link to another database table	Link outputs a number that is a meaningful reference for the database but not of much use to a human user. You will usually want to drill further down the tree in the Sources pane and select fields from the linked table. However, in some instances you might want to use a link field. For example, to count the number of patrons who borrowed items you could do a count on the Patron link data.

When to use what?

Select the org_units data type when working with Base Filters;
Select text, money when working with selecting columns for a report;
Select id when working with counts and aggregate filters; Also use id when working with circulation modifier selection within the Base Filters pane.
Select bool when working with true/false fields for example Active? Or Deleted?
Links are not selectable for display or report inclusion; A link field means you MUST find your data field in another part of the data source tree.

Knowledge Tags

This page was: Helpful | Not Helpful