HomeReports in EvergreenAppendicesAppendix A: Data Types

1. Appendix A: Data Types

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


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 field

Usually uses the Raw Data transform.


Exact date and time

Select appropriate date/time transform. Raw Data includes second and timezone information, usually more than is required for a report.


True or False

Commonly used to filter out deleted item or patron records.


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.


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?


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