# How to use Rollup to count instances in a relational column? **URL:** \ **Category:** Ask for Help\ **Created:** [February 3, 2022, 6:14pm UTC](https://community.glideapps.com/t/how-to-use-rollup-to-count-instances-in-a-relational-column/38082 "2022-02-03T18:14:04Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![3dyuval](https://sea2.discourse-cdn.com/flex002/user_avatar/community.glideapps.com/3dyuval/32/37504_2.png) [@3dyuval](https://community.glideapps.com/u/3dyuval)\ **Post date:** [February 3, 2022, 6:14pm UTC](https://community.glideapps.com/t/how-to-use-rollup-to-count-instances-in-a-relational-column/38082/1 "2022-02-03T18:14:04Z")
Hey, I’m using Glide App to create a material lists organized into categories. My goal is to count the number of materials in each category. This is a relational column that looks at another table for a category to match to all materials. Why this doesn’t work? ![roll](https://us1.discourse-cdn.com/flex002/uploads/glideapps/original/3X/b/3/b33486c2a7b05f701d6878c91ecb7a40a7674a3e.jpeg) ---
**Author:** ![SantiagoPerez](https://sea2.discourse-cdn.com/flex002/user_avatar/community.glideapps.com/santiagoperez/32/16807_2.png) [@SantiagoPerez](https://community.glideapps.com/u/SantiagoPerez)\ **Post date:** [February 3, 2022, 6:20pm UTC](https://community.glideapps.com/t/how-to-use-rollup-to-count-instances-in-a-relational-column/38082/2 "2022-02-03T18:20:06Z")
If you want the info (rollup) from the relation, you need to select “Category?Materials” them one of the two columns either title or description. ---
**Author:** ![ThinhDinh](https://sea2.discourse-cdn.com/flex002/user_avatar/community.glideapps.com/thinhdinh/32/49_2.png) [@ThinhDinh](https://community.glideapps.com/u/ThinhDinh)\ **Post date:** [February 3, 2022, 11:43pm UTC](https://community.glideapps.com/t/how-to-use-rollup-to-count-instances-in-a-relational-column/38082/3 "2022-02-03T23:43:18Z")
Adding to this, then use a “Count” method to return the correct instances.