Table relationships allow you to easily connect and link rows together between multiple tables, to help represent concepts of data relating to each other: for example, a row in a Projects table may be linked to rows in a Teams table to denote that a project is owned or assigned to a team. However, to ensure these relationships work, you need to make sure the tables, rows, and columns all exist and are properly linked together.
In this article, we share some potential issues that you may run into when working with relationships. When one of these parts of a relationship are missing or deleted or changed, it can break the relationship so it doesn't behave as intended.
Missing linked row
With a table relationship, you link from one table to another table (the current table creates a link to a "source table"), and you can create Lookup columns that let you select rows from the source table, to link to the row in your table. For example, you can create a Lookup to let you select rows from the Teams table, to link to a project in the Projects table.
If the linked row is deleted from the source table, the data will still show up in your current table, but it will show an warning icon with an error message explaining that the linked row is missing:
How to fix
- If you don't want to restore the linked row, and just want to clear the error, you can simply select the cell and hit "Backspace" or "Delete" to remove the broken linked value. You can also edit the cell and link to a new row instead.
- If you recently deleted the linked row, go back to the source table and undo the deletion.
- If someone else deleted the linked row or if it was deleted a while ago, you can try to find the deleted row in the source table's change history and restore it.
Missing source column
When creating the Lookup column, you can specify which "source column" to show data from the linked row. For example, the Projects table may link to the Teams table, and we want to only show the "Team Name" column from the Teams table.
If the source column for a Lookup is deleted or changes its type, then after a week, your Lookup column's values may eventually be broken or show invalid information. This happens because the original source column is kept temporarily in change history for undo/restoration purposes, and then after a week, it will be deleted permanently.
You will also see the missing source column if you view the relationship in the Relationships dialog.
How to fix
NOTE: if you delete the last Lookup column for a relationship, it will delete the relationship and all the links between the rows will be lost.
To preserve the existing links in your table while fixing the broken linked column, you can:
- Add a second Lookup column that uses the same relationship (don't create a new relationship) and shows data from another column (not the one you want to show), then delete the broken linked column, and finally add one more Lookup column that DOES show the column you want.
- For example:
- In the Projects table we have a Lookup column named "Owner" that shows data from the "Team Name" column in Teams, and we linked some projects to the teams that own them.
- If the source "Team Name" column is deleted or changed type, a week later the "Owner" Lookup column in Projects will look broken.
- To fix this, we will add a new Lookup column named "Region" that uses the same relationship to pull in the "Team Location" for each linked team.
- Then we delete the broken "Owner" Lookup column.
- Finally, we add a new "Owner" Lookup column, using the same relationship, and select the correct "Team Name" column to show.
- You can apply this fix via the Add Column dialog or via the Relationships dialog flow, either should work.
Missing linked table
If someone deletes the source table that your rows are linked to, the data in your Lookup columns will still exist, but will eventually show a warning/error in the Lookup column header, indicating that the table is unavailable. Users will not be able to select rows to link to, since there is no source table to read from.
How to fix
- If you are the table owner, you can try to find the deleted table in your Trash and restore it.
- If someone else owns the table, you will need to contact the owner and ask them to restore the table.
- If you don't care about restoring the table and links, you can simply delete the Lookup column or convert it to Text or another type to preserve the data.
Missing table permission
When someone creates a relationship between two tables, it also creates a table-to-table permission. To prevent abuse or malicious activity -- for example, if you don't want someone to be linking to data in your table -- you can remove the table-to-table permission.
If someone removes this table-to-table permission, the data in your Lookup columns will still exist, but will eventually show a warning/error in the Lookup column header, indicating that the table is unavailable. Users will not be able to select rows to link to, since there is no source table to read from.
How to fix
- If you are the table owner, you need to go to the source table and open the "Table settings" dialog and restore the blocked table-to-table permission.
- If someone else owns the table, you will need to contact the owner and ask them to restore the blocked permission.