Error messages and what they mean
Stata's error messages are usually clear, but it's not always obvious what you can do about them. Here are a few that could use a little explanation.
1. too many values
This error message can result from a 2-way tabulation of variables that each have a lot of values. If you really want to cross-tabulate these two variables, you can do it in pieces, limiting the range of one or the other variable in each tabulation:
tab2 var1 var2 if var1 <= 10 tab2 var1 var2 if var1 > 10 & var1 <= 20 etc.
2. no: data in memory would be lost
If you make any changes in the data currently in memory, then try to exit Stata, you'll get this message. Stata is reminding you that you have not saved the data in memory since making the changes. You can either save the data, if you want to keep the changes, or clear the data from memory, if you don't want to keep the changes. Then exit.