problem in sorting data

[rahul kumar singh]

I am using Stata 15.1, I have a large data set of labor supply by households. i want to sort my data by HH_ID, PRE_MEM_ID but I got many missing data after sorting. all the variables of data are in string form. I have attached the data below. Please help me? one more detail about data is that I have prepared this by appending data from many data files

[Leonardo Guizzetti]

Hi Rahul,

We ask that you don't provide file attachments as many people, including myself, will not open unknown attachments. You are so encouraged to provide a data example using -dataex-. All of this is described in the FAQ which you are prompted to read when you post.

That said, you are seeing missing values because you have missing values. Whether they should be there or not depends on how the data were collected and manipulated, including perhaps how you appended datasets. If these household ids are missing then that will be a problem, but more likely to be caused by something you have done rather than an actual missing identifier from the source.