How do I validate child table rows, such as a column total of 100 or unique values?

Short answer: Total the column with an aggregation field, then add a validation on the Submit action. For unique values in one column, turn on Mark as unique.

Why it happens

Table validations check one cell or the row count. A rule across all rows, like a total, needs an aggregation field outside the table.

How to fix it

To require a column total of 100:

1. Add an aggregation field with Aggregate table data in the context of a single item of the process turned on, and SUM the column.
2. In the process editor, open Permissions, select the step, and click Configure actions.
3. Hover over Submit, click Advanced, and add a validation that the aggregation field equals 100. See configuring actions.

To require unique values in a column:

1. Select the column and turn on Mark as unique. See unique fields in child tables.

2. Each table can have one unique column, of type Text, Number, Date, Dropdown, Email, Radio or Scanner. Optionally, enter a custom error message.