Rollup Field in Baserow: Aggregate Data from Linked Rows
A Rollup field runs a calculation - sum, average, count, and more - across every row linked through a Link to table field and shows the result right in the current table; this article covers how it differs from a Lookup or Count field, how to create one, and how to read the table of available functions.
What a Rollup field is
A Rollup field works on top of an existing Link to table field . While a Lookup field simply displays one piece of data from a linked row (an email address, say), a Rollup field runs a calculation across all the linked rows at once - a sum, an average, a minimum, a maximum, and so on.
The field is read-only: you cannot edit its value directly. It is an automatic calculation that recalculates every time the data in the linked rows changes.
How to create a Rollup field
Prerequisite
You need an existing Link to table field in the table before you can create a Rollup field.
Steps
- In the table, click the
+icon to add a new field . - Enter a name for the field, for example “Total Spent” or “Average Rating”.
- Select Rollup from the field type dropdown.
- In the configuration panel, set three options:
- Link row field: pick the Link to table field that supplies the linked rows;
- Field to roll up: pick the specific field in the linked table whose values you want to aggregate, for example “Order Amount”;
- Rollup function: pick the calculation to run, for example
sum.
- Click Create.
The new field is populated immediately with the calculation result and stays read-only from then on.
Rollup functions
A Rollup field supports several aggregation functions. The function you pick must be compatible with the type of the field being aggregated - you can only sum a Number field
, for instance.
| Function | Description | Compatible field types |
|---|---|---|
sum | Adds all values together | Number |
avg | Calculates the average of all values | Number |
count | Returns the number of linked rows | Any type |
max | Returns the highest value | Number , Date , Text |
min | Returns the lowest value | Number , Date , Text |
any | Returns true if any linked boolean value is true | Boolean |
every | Returns true if every linked boolean value is true | Boolean |
stddev_sample | Sample standard deviation | Number |
stddev_pop | Population standard deviation | Number |
variance_sample | Sample variance | Number |
variance_pop | Population variance | Number |
Example: customers and orders
This is the clearest way to see what a Rollup field does. Say there are two tables, and the goal is to show the total amount each customer has spent directly on the Customers table.
- Customers: holds a “Customer Name” field.
- Orders: holds “Order ID”, a Number field called “Order Amount”, and a Link to table field called “[Link] Customer”.
Solution: on the Customers table, create a Rollup field named “Total Spent”:
- Link row field: pick the “[Link] Customer” field;
- Field to roll up: pick the “Order Amount” field from the Orders table;
- Rollup function: pick
sum.
The “Total Spent” field now calculates and displays the sum of every linked order for each customer automatically, for example “$150.00”.
Frequently asked questions
What’s the difference between Rollup, Lookup, and Count? All three build on a Link to table field , but they solve different jobs: Link to table creates the relationship between rows; Lookup displays one specific value from a linked row, such as a customer’s email; Count counts the linked rows, such as “3 orders”; Rollup runs a calculation across the linked rows, such as the sum of “Order Amount”.
How is the Rollup count function different from a dedicated Count field? The result is identical. The Count field
is a simpler, dedicated field type built for exactly that one job, while count in a Rollup field is just one of the many functions available there.
Why can’t a Rollup field be edited? It is a read-only field that displays a calculation result. To change its value, change the data in the linked rows instead - add a new order, or update an existing order’s amount.
What’s next
Read up on the Link to table field to see how relationships between tables are built, the Lookup field for displaying single values from linked rows, and the Count field for a simple linked-row count. Field Types Overview compares Rollup against every other computed field type, and Field Configuration covers sorting, filtering, and hiding for any field type, Rollup included.