Thank you for your post and welcome to the community!
I see that you are looking to include data from your ‘Vehicles Table’ with the related ‘Mobile No’ from the ‘Member Table’. I see that you also specified that there is ‘Mobile No’ information in the ‘Vehicles Table’ as well. I’ll assume that the ‘Mobile No’ from the two tables are different from each other.
What you will want to do is create a Rowlink for column ‘Flat No’ in the ‘Vehicles Table’ that links back to the ‘Member Table’. This will create the connection between the two tables. After you do this, in your ‘Vehicles Table’ you can create another column called ‘Member Mobile No’ and this is where you can insert the corresponding members ‘Mobile No’. Since you created a rowlink, you can easily do this by creating a formula for column ‘Member Mobile No’ that pulls the corresponding ‘Mobile No’. The formula would looks something like this =[Flat No][Mobile No] . Here is a screenshot of the formula in my sample table and what it is referring to:
Now, in your app you can create a list that shows the correct member mobile number with all your vehicles.
Check out our Explorer Series video (Explorer Series Video: Rowlinks and Picklists) on Rowlinks, this will give you a great live product walk through on how this works.
If this doesn’t help, could you include some screenshots of sample tables and what you tried in app builder? I’m more than happy to help!